There have been quite a few Reddit posts recently about text input being slow that were fixed by setting accessibility.force_disabled to 1:
https://old.reddit.com/r/firefox/comments/ypzizc/having_massive_lag_issues_in_all_textboxes_in_ff/
https://old.reddit.com/r/firefox/comments/yp9gfg/cpu_usage_spikes_when_writing_emails/
https://old.reddit.com/r/firefox/comments/yqgoa7/typing_issue_in_every_textbox_search_bar_whatsapp/
These don't mention copying to the clipboard, so this probably isn't Suggested Actions (bug 1774285). This is a fairly recent spike, so this probably isn't Text Cursor Indicator (bug 1668695), which has to be explicitly enabled and has been around for a while.
Unfortunately, we don't have any details beyond this at this point. There's a tendency for people to recommend disabling accessibility without reporting the problem, providing a profile and/or providing other details. Nevertheless, I'm filing this bug so we have somewhere to track this.
I suspect that Cache the World will improve this. Even though there's clearly some a11y client on these systems that is doing something inefficient, Cache the World will at least make that faster and might make it unnoticeable.

[Tracking Requested - why for this release]:

https://www.reddit.com/r/firefox/comments/ype64p/lag_while_erasing_text/
https://www.reddit.com/r/firefox/comments/yvdihl/when_i_type_on_websites_like_fast_it_gets_delayed/

Tracking to keep on the radar for a potential release uplift. Though, this is not new in 107.
:jamie what priority does this have?
Do you plan on investigating for a short term fix before Cache the World is ready?

do we know if there's any linkage to specific OS/versions?

I'm bumping this to s2 given the number of reports we're seeing about this. However, none of these reports are coming in via Bugzilla and none of them have sufficient information to be actionable. I guess I might have to dive into Reddit if all else fails.

Matt, over in bug 1748980, you noted that you thought you were seeing that and I suggested you might be seeing this instead. Would you mind providing the following information?

1. Go to about:support using the address bar and provide the information from there.
2. What is your computer manufacturer and model?
3. Do you have any accessibility tools, enterprise SSO tools or security software installed? If so, what?
4. Are you able to provide a performance profile during the freeze? See this page for instructions.

Thanks for any help you can provide.

1. attached
2. HP Envy 15
3. No accessibility tools, only the security software that comes with Windows
4. https://share.firefox.dev/3ggN5ei

I've been noticing this on lots of sites. Actually, just happened here writing this comment.

Setting accessibilty.force_disabled works!

I have the copy of reddit users' about:support information who didn't agree to have it posted publicly. Here is just a snippet from the accessibility section. (Contact me for the whole info, if useful)

Accessibility
-------------
Activated: true
Prevent Accessibility: 0
Accessible Handler Used: true
Accessibility Instantiator: UNKNOWN|

Intriguing. Both Matt (this bug) and Karen (bug 1800809) have HP Envy computers.

Tom, any chance you could ask the Reddit user you were in touch with what computer they're using?

Cache the World is enabled for Matt (who is running Nightly), so it seems that doesn't help here. Looking at the profile, some a11y client is either making an awful number of pointless calls to get the parent of the root window or making a few such calls which are taking a very long time (potentially because something is hooking window messages and causing delays).

Unfortunately, we don't seem to be able to determine what executable is triggering accessibility on Matt's system, nor the system of the Reddit user mentioned in comment 9.

Tom, any chance you could ask the Reddit user you were in touch with what computer they're using?

HP OMEN 15-en0008na

The bug is marked as tracked for firefox107 (release). However, the bug still isn't assigned.

:fgriffith, could you please find an assignee for this tracked bug? If you disagree with the tracking decision, please talk with the release managers.

For more information, please visit auto_nag documentation.

Jamie will be assigned. Monitoring for additional input but may have to consider acquiring HP laptop to investigate further.

Could someone experiencing this please provide the information from the about:third-party page? Thanks.