High CPU usage with harfbuzz 7.0

[chrs8]

After upgrading harfbuzz from 6.0 to 7.0 I observe high CPU usage when scrolling inside neovim in kitty terminal (see kovidgoyal/kitty#6030)

Investigating with perf top reveals:

Overhead  Shared Object                   Symbol
  56,65%  libfreetype.so.6.19.0           [.] TT_RunIns

These calls don't occur with harfbuzz 6.0

[behdad]

Humm. We didn't make any changes in how we interact with freetype.

[chrs8]

Any hints where I could investigate further?

[behdad]

Does the upgrading to HB7 also upgrade FreeType by any chance?

[chrs8]

I'm on Archlinux and this issue came with the update of harfbuzz, freetype was upgraded a couple of days earlier.
Current config:
Freetype2 2.13.0
Harfbuzz 7.0.1
-> the issue as described

If I downgrade Harfbuzz to 6.0.0 with everything else unchanged
-> no problem

[behdad]

Okay I did change some. My bad I think. Let me get to the bottom of this.

[behdad]

Fixed it I think. Any chance you can test?

[chrs8]

tbh, as I haven't done this before, I'd rather not mess with compiling and installing such a "low level" package myself. I will report back when the next release has made it to the arch repo.

Thank you for the fast response.

[chrs8]

Ok, I decided to take the risk and tested it.

The problem is fixed!