diff --git a/.evergreen/build-mac.sh b/.evergreen/build-mac.sh
deleted file mode 100755
index 4e8be8cf5..000000000
--- a/.evergreen/build-mac.sh
+++ /dev/null
@@ -1,30 +0,0 @@
-#!/bin/bash -ex
-
-# Get access to testinstall.
-. .evergreen/utils.sh
-
-# Create temp directory for validated files.
-rm -rf validdist
-mkdir -p validdist
-mv dist/* validdist || true
-
-VERSION=${VERSION:-3.10}
-
-PYTHON=/Library/Frameworks/Python.framework/Versions/$VERSION/bin/python3
-rm -rf build
-
-createvirtualenv $PYTHON releasevenv
-python -m pip install build
-python -m build --wheel .
-deactivate || true
-rm -rf releasevenv
-
-# Test that each wheel is installable.
-for release in dist/*; do
-    testinstall $PYTHON $release
-    mv $release validdist/
-done
-
-mv validdist/* dist
-rm -rf validdist
-ls dist
diff --git a/.evergreen/build-manylinux-internal.sh b/.evergreen/build-manylinux-internal.sh
deleted file mode 100755
index 267e647ff..000000000
--- a/.evergreen/build-manylinux-internal.sh
+++ /dev/null
@@ -1,42 +0,0 @@
-#!/bin/bash -ex
-cd /src
-
-# Get access to testinstall.
-. .evergreen/utils.sh
-
-# Create temp directory for validated files.
-rm -rf validdist
-mkdir -p validdist
-mv dist/* validdist || true
-
-# Compile wheels
-for PYTHON in /opt/python/*/bin/python; do
-    if [[ ! $PYTHON =~ (cp38|cp39|cp310|cp311|cp312) ]]; then
-        continue
-    fi
-    # https://github.com/pypa/manylinux/issues/49
-    rm -rf build
-    $PYTHON -m pip install build
-    $PYTHON -m build --wheel .
-    rm -rf build
-
-    # Audit wheels and write manylinux tag
-    for whl in dist/*.whl; do
-        # Skip already built manylinux wheels.
-        if [[ "$whl" != *"manylinux"* ]]; then
-            auditwheel repair $whl -w dist
-            rm $whl
-        fi
-    done
-
-    # Test that each wheel is installable.
-    # Test without virtualenv because it's not present on manylinux containers.
-    for release in dist/*; do
-        testinstall $PYTHON $release "without-virtualenv"
-        mv $release validdist/
-    done
-done
-
-mv validdist/* dist
-rm -rf validdist
-ls dist
diff --git a/.evergreen/build-manylinux.sh b/.evergreen/build-manylinux.sh
deleted file mode 100755
index 19f2b7f4a..000000000
--- a/.evergreen/build-manylinux.sh
+++ /dev/null
@@ -1,50 +0,0 @@
-#!/bin/bash -ex
-
-docker version
-
-# Set up qemu support using the method used in docker/setup-qemu-action
-# https://github.com/docker/setup-qemu-action/blob/2b82ce82d56a2a04d2637cd93a637ae1b359c0a7/README.md?plain=1#L46
-docker run --rm --privileged tonistiigi/binfmt:latest --install all
-
-# manylinux1 2021-05-05-b64d921 and manylinux2014 2021-05-05-1ac6ef3 were
-# the last releases to generate pip < 20.3 compatible wheels. After that
-# auditwheel was upgraded to v4 which produces PEP 600 manylinux_x_y wheels
-# which requires pip >= 20.3. We use the older docker image to support older
-# pip versions.
-BUILD_WITH_TAG="$1"
-if [ -n "$BUILD_WITH_TAG" ]; then
-  images=(quay.io/pypa/manylinux1_x86_64:2021-05-05-b64d921 \
-          quay.io/pypa/manylinux1_i686:2021-05-05-b64d921 \
-          quay.io/pypa/manylinux2014_x86_64:2021-05-05-1ac6ef3 \
-          quay.io/pypa/manylinux2014_i686:2021-05-05-1ac6ef3 \
-          quay.io/pypa/manylinux2014_aarch64:2021-05-05-1ac6ef3 \
-          quay.io/pypa/manylinux2014_ppc64le:2021-05-05-1ac6ef3 \
-          quay.io/pypa/manylinux2014_s390x:2021-05-05-1ac6ef3)
-else
-  images=(quay.io/pypa/manylinux1_x86_64 \
-          quay.io/pypa/manylinux1_i686 \
-          quay.io/pypa/manylinux2014_x86_64 \
-          quay.io/pypa/manylinux2014_i686 \
-          quay.io/pypa/manylinux2014_aarch64 \
-          quay.io/pypa/manylinux2014_ppc64le \
-          quay.io/pypa/manylinux2014_s390x)
-fi
-
-for image in "${images[@]}"; do
-  docker pull $image
-  docker run --rm -v "`pwd`:/src" $image /src/.evergreen/build-manylinux-internal.sh
-done
-
-ls dist
-
-# Check for any unexpected files.
-unexpected=$(find dist \! \( -iname dist -or \
-                             -iname '*cp38*' -or \
-                             -iname '*cp39*' -or \
-                             -iname '*cp310*' -or \
-                             -iname '*cp311*' -or \
-                             -iname '*cp312*' \))
-if [ -n "$unexpected" ]; then
-  echo "Unexpected files:" $unexpected
-  exit 1
-fi
diff --git a/.evergreen/build-windows.sh b/.evergreen/build-windows.sh
deleted file mode 100755
index d30382fce..000000000
--- a/.evergreen/build-windows.sh
+++ /dev/null
@@ -1,29 +0,0 @@
-#!/bin/bash -ex
-
-# Get access to testinstall.
-. .evergreen/utils.sh
-
-# Create temp directory for validated files.
-rm -rf validdist
-mkdir -p validdist
-mv dist/* validdist || true
-
-for VERSION in 38 39 310 311 312; do
-    _pythons=("C:/Python/Python${VERSION}/python.exe" \
-              "C:/Python/32/Python${VERSION}/python.exe")
-    for PYTHON in "${_pythons[@]}"; do
-        rm -rf build
-        $PYTHON -m pip install build
-        $PYTHON -m build --wheel .
-
-        # Test that each wheel is installable.
-        for release in dist/*; do
-            testinstall $PYTHON $release
-            mv $release validdist/
-        done
-    done
-done
-
-mv validdist/* dist
-rm -rf validdist
-ls dist
diff --git a/.evergreen/config.yml b/.evergreen/config.yml
index 8f32b8a1b..1e218e2c7 100644
--- a/.evergreen/config.yml
+++ b/.evergreen/config.yml
@@ -786,92 +786,6 @@ functions:
         args:
           - ${DRIVERS_TOOLS}/.evergreen/atlas/teardown-atlas-cluster.sh
 
-  "build release":
-    - command: shell.exec
-      type: test
-      params:
-        working_dir: "src"
-        script: |
-          ${PREPARE_SHELL}
-          set -o xtrace
-          VERSION=${VERSION} ENSURE_UNIVERSAL2=${ENSURE_UNIVERSAL2} .evergreen/release.sh
-
-  "upload release":
-    - command: ec2.assume_role
-      params:
-        role_arn: ${assume_role_arn}
-    - command: archive.targz_pack
-      params:
-        target: "release-files.tgz"
-        source_dir: "src/dist"
-        include:
-          - "*"
-    - command: s3.put
-      params:
-        aws_key: ${AWS_ACCESS_KEY_ID}
-        aws_secret: ${AWS_SECRET_ACCESS_KEY}
-        aws_session_token: ${AWS_SESSION_TOKEN}
-        local_file: release-files.tgz
-        remote_file: release/${revision}/${task_id}-${execution}-release-files.tar.gz
-        bucket: ${bucket_name}
-        permissions: public-read
-        content_type: ${content_type|application/gzip}
-        display_name: Release files
-
-  "download and merge releases":
-    - command: ec2.assume_role
-      params:
-        role_arn: ${assume_role_arn}
-    - command: shell.exec
-      params:
-        silent: true
-        include_expansions_in_env: ["AWS_ACCESS_KEY_ID", "AWS_SECRET_ACCESS_KEY", "AWS_SESSION_TOKEN"]
-        script: |
-          # Download all the task coverage files.
-          aws s3 cp --recursive s3://${bucket_name}/release/${revision}/ release/
-    - command: shell.exec
-      params:
-        shell: "bash"
-        script: |
-          ${PREPARE_SHELL}
-          set -o xtrace
-          # Combine releases into one directory.
-          ls -la release/
-          mkdir releases
-          # Copy old manylinux release first since we want the newer manylinux
-          # wheels to override them.
-          mkdir old_manylinux
-          if mv release/*old_manylinux* old_manylinux; then
-            for REL in old_manylinux/*; do
-              tar zxvf $REL -C releases/
-            done
-          fi
-          for REL in release/*; do
-            tar zxvf $REL -C releases/
-          done
-          # Build source distribution.
-          cd src/
-          /opt/python/3.8/bin/python3 -m pip install build
-          /opt/python/3.8/bin/python3 -m build --sdist .
-          cp dist/* ../releases
-    - command: archive.targz_pack
-      params:
-        target: "release-files-all.tgz"
-        source_dir: "releases/"
-        include:
-          - "*"
-    - command: s3.put
-      params:
-        aws_key: ${AWS_ACCESS_KEY_ID}
-        aws_secret: ${AWS_SECRET_ACCESS_KEY}
-        aws_session_token: ${AWS_SESSION_TOKEN}
-        local_file: release-files-all.tgz
-        remote_file: release-all/${revision}/${task_id}-${execution}-release-files-all.tar.gz
-        bucket: ${bucket_name}
-        permissions: public-read
-        content_type: ${content_type|application/gzip}
-        display_name: Release files all
-
   "run perf tests":
     - command: shell.exec
       type: test
@@ -1116,72 +1030,6 @@ tasks:
                genhtml --version || true
                valgrind --version || true
 
-    - name: "release-mac"
-      tags: ["release_tag"]
-      run_on: macos-11
-      commands:
-        - func: "build release"
-          vars:
-              VERSION: "3.12"
-              ENSURE_UNIVERSAL2: "1"
-        - func: "build release"
-          vars:
-              VERSION: "3.11"
-              ENSURE_UNIVERSAL2: "1"
-        - func: "build release"
-          vars:
-              VERSION: "3.10"
-              ENSURE_UNIVERSAL2: "1"
-        - func: "build release"
-          vars:
-              VERSION: "3.9"
-              ENSURE_UNIVERSAL2: "1"
-        - func: "upload release"
-        - func: "build release"
-          vars:
-              VERSION: "3.8"
-        - func: "upload release"
-
-    - name: "release-windows"
-      tags: ["release_tag"]
-      run_on: windows-64-vsMulti-small
-      commands:
-        - func: "build release"
-        - func: "upload release"
-
-    - name: "release-manylinux"
-      tags: ["release_tag"]
-      run_on: ubuntu2204-large
-      exec_timeout_secs: 216000  # 60 minutes (manylinux task is slow).
-      commands:
-        - func: "build release"
-        - func: "upload release"
-
-    - name: "release-old-manylinux"
-      tags: ["release_tag"]
-      run_on: ubuntu2204-large
-      exec_timeout_secs: 216000  # 60 minutes (manylinux task is slow).
-      commands:
-        - command: shell.exec
-          type: test
-          params:
-            working_dir: "src"
-            script: |
-              ${PREPARE_SHELL}
-              set -o xtrace
-              .evergreen/build-manylinux.sh BUILD_WITH_TAG
-        - func: "upload release"
-
-    - name: "release-combine"
-      tags: ["release_tag"]
-      run_on: rhel84-small
-      depends_on:
-        - name: "*"
-          variant: ".release_tag"
-          patch_optional: true
-      commands:
-        - func: "download and merge releases"
-
 # Standard test tasks {{{
 
     - name: "mockupdb"
@@ -3177,13 +3025,6 @@ buildvariants:
   tasks:
     - name: "check-import-time"
 
-- name: Release
-  display_name: Release
-  batchtime: 20160 # 14 days
-  tags: ["release_tag"]
-  tasks:
-  - ".release_tag"
-
 - name: "perf-tests"
   display_name: "Performance Benchmark Tests"
   batchtime: 10080  # 7 days
diff --git a/.evergreen/hatch.sh b/.evergreen/hatch.sh
index e24320b9d..843839410 100644
--- a/.evergreen/hatch.sh
+++ b/.evergreen/hatch.sh
@@ -13,8 +13,11 @@ if $PYTHON_BINARY -m hatch --version; then
       $PYTHON_BINARY -m hatch run "$@"
     }
 else # No toolchain hatch present, set up virtualenv before installing hatch
-    createvirtualenv "$PYTHON_BINARY" hatchenv
-    trap "deactivate; rm -rf hatchenv" EXIT HUP
+    # Use a random venv name because the encryption tasks run this script multiple times in the same run.
+    ENV_NAME=hatchenv-$RANDOM
+    createvirtualenv "$PYTHON_BINARY" $ENV_NAME
+    # shellcheck disable=SC2064
+    trap "deactivate; rm -rf $ENV_NAME" EXIT HUP
     python -m pip install -q hatch
     run_hatch() {
       python -m hatch run "$@"
diff --git a/.evergreen/release.sh b/.evergreen/release.sh
deleted file mode 100755
index 1fdd459ad..000000000
--- a/.evergreen/release.sh
+++ /dev/null
@@ -1,9 +0,0 @@
-#!/bin/bash -ex
-
-if [ "$(uname -s)" = "Darwin" ]; then
-    .evergreen/build-mac.sh
-elif [ "Windows_NT" = "$OS" ]; then # Magic variable in cygwin
-    .evergreen/build-windows.sh
-else
-    .evergreen/build-manylinux.sh
-fi
diff --git a/.evergreen/utils.sh b/.evergreen/utils.sh
index ff186c6e1..1a5e2a153 100755
--- a/.evergreen/utils.sh
+++ b/.evergreen/utils.sh
@@ -43,7 +43,7 @@ find_python3() {
 createvirtualenv () {
     PYTHON=$1
     VENVPATH=$2
-    rm -rf $VENVPATH
+
     # Prefer venv
     VENV="$PYTHON -m venv"
     if [ "$(uname -s)" = "Darwin" ]; then
diff --git a/.github/workflows/test-python.yml b/.github/workflows/test-python.yml
index 4d514726c..ba04e8e41 100644
--- a/.github/workflows/test-python.yml
+++ b/.github/workflows/test-python.yml
@@ -78,9 +78,6 @@ jobs:
       - name: Run tests
         run: |
           hatch run test:test
-      - name: Run async tests
-        run: |
-          hatch run test:test-async
 
   doctest:
     runs-on: ubuntu-latest
diff --git a/bson/objectid.py b/bson/objectid.py
index 57efdc798..a5500872d 100644
--- a/bson/objectid.py
+++ b/bson/objectid.py
@@ -29,6 +29,9 @@ from bson.errors import InvalidId
 from bson.tz_util import utc
 
 _MAX_COUNTER_VALUE = 0xFFFFFF
+_PACK_INT = struct.Struct(">I").pack
+_PACK_INT_RANDOM = struct.Struct(">I5s").pack
+_UNPACK_INT = struct.Struct(">I").unpack
 
 
 def _raise_invalid_id(oid: str) -> NoReturn:
@@ -132,7 +135,7 @@ class ObjectId:
         if offset is not None:
             generation_time = generation_time - offset
         timestamp = calendar.timegm(generation_time.timetuple())
-        oid = struct.pack(">I", int(timestamp)) + b"\x00\x00\x00\x00\x00\x00\x00\x00"
+        oid = _PACK_INT(int(timestamp)) + b"\x00\x00\x00\x00\x00\x00\x00\x00"
         return cls(oid)
 
     @classmethod
@@ -163,18 +166,12 @@ class ObjectId:
 
     def __generate(self) -> None:
         """Generate a new value for this ObjectId."""
-        # 4 bytes current time
-        oid = struct.pack(">I", int(time.time()))
-
-        # 5 bytes random
-        oid += ObjectId._random()
-
-        # 3 bytes inc
         with ObjectId._inc_lock:
-            oid += struct.pack(">I", ObjectId._inc)[1:4]
-            ObjectId._inc = (ObjectId._inc + 1) % (_MAX_COUNTER_VALUE + 1)
+            inc = ObjectId._inc
+            ObjectId._inc = (inc + 1) % (_MAX_COUNTER_VALUE + 1)
 
-        self.__id = oid
+        # 4 bytes current time, 5 bytes random, 3 bytes inc.
+        self.__id = _PACK_INT_RANDOM(int(time.time()), ObjectId._random()) + _PACK_INT(inc)[1:4]
 
     def __validate(self, oid: Any) -> None:
         """Validate and use the given id for this ObjectId.
@@ -212,7 +209,7 @@ class ObjectId:
         represents the generation time in UTC. It is precise to the
         second.
         """
-        timestamp = struct.unpack(">I", self.__id[0:4])[0]
+        timestamp = _UNPACK_INT(self.__id[0:4])[0]
         return datetime.datetime.fromtimestamp(timestamp, utc)
 
     def __getstate__(self) -> bytes:
diff --git a/test/asynchronous/test_cursor.py b/test/asynchronous/test_cursor.py
index 833493ce3..d6d56244f 100644
--- a/test/asynchronous/test_cursor.py
+++ b/test/asynchronous/test_cursor.py
@@ -1380,7 +1380,6 @@ class TestCursor(AsyncIntegrationTest):
         self.assertEqual("getMore", started[1].command_name)
         self.assertNotIn("$readPreference", started[1].command)
 
-    @async_client_context.require_version_min(4, 0)
     @async_client_context.require_replica_set
     async def test_to_list_tailable(self):
         oplog = self.client.local.oplog.rs
@@ -1391,7 +1390,10 @@ class TestCursor(AsyncIntegrationTest):
             {"ts": {"$gte": ts}}, cursor_type=pymongo.CursorType.TAILABLE_AWAIT, oplog_replay=True
         ).max_await_time_ms(1)
         self.addAsyncCleanup(c.close)
-        docs = await c.to_list()
+        # Wait for the change to be read.
+        docs = []
+        while not docs:
+            docs = await c.to_list()
         self.assertGreaterEqual(len(docs), 1)
 
     async def test_to_list_empty(self):
diff --git a/test/test_cursor.py b/test/test_cursor.py
index e995bd529..0d6186519 100644
--- a/test/test_cursor.py
+++ b/test/test_cursor.py
@@ -1371,7 +1371,6 @@ class TestCursor(IntegrationTest):
         self.assertEqual("getMore", started[1].command_name)
         self.assertNotIn("$readPreference", started[1].command)
 
-    @client_context.require_version_min(4, 0)
     @client_context.require_replica_set
     def test_to_list_tailable(self):
         oplog = self.client.local.oplog.rs
@@ -1382,7 +1381,10 @@ class TestCursor(IntegrationTest):
             {"ts": {"$gte": ts}}, cursor_type=pymongo.CursorType.TAILABLE_AWAIT, oplog_replay=True
         ).max_await_time_ms(1)
         self.addCleanup(c.close)
-        docs = c.to_list()
+        # Wait for the change to be read.
+        docs = []
+        while not docs:
+            docs = c.to_list()
         self.assertGreaterEqual(len(docs), 1)
 
     def test_to_list_empty(self):