Bug report

Bug description:

When running the code below it causes ~143,000 disk operations to read in the entire file. This is because it is doing 2 bytes at a time for some reason.

import ssl
import certifi

ssl.create_default_context(cafile=certifi.where())

How to replicate

1. Download & Run Procmon https://learn.microsoft.com/en-us/sysinternals/downloads/procmon
2. Make sure you aren't running any other Python code to make the capture easier
3. In the filter window have it filter for Process Name contains python

4. Make sure Procmon is capturing
5. Run the python program above
6. Observe all the disk operations

If reading the file normally with open then it behaves as expected and only does a handful of calls

CPython versions tested on:

3.13

Operating systems tested on:

Windows

Linked PRs

• gh-137560: Speed up ssl.create_default_context() on Windows #137596