Bug report

Bug description:

Bug Description:
A series of performance issues related to quadratic complexity has been identified in IDLE's editor. On files with very long lines, this can cause the editor to freeze or hang.

Vulnerability Locations:

• 1 (Fixed): https://github.com/python/cpython/blob/5ab66a882d1b5e44ec50b25df116ab209d65863f/Lib/idlelib/editor.py#L1206
• 2 (Not need fix): https://github.com/python/cpython/blob/5ab66a882d1b5e44ec50b25df116ab209d65863f/Lib/idlelib/editor.py#L1373

Repair Status:

• Issues 1 have been fixed by @johnzhou721.
• gh-136061: IDLE - update code in editor.Editor.load_extension #134874

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-136061: IDLE - update code in editor.Editor.load_extension #134874