Javanese text *seriously* degrades performance

So long as Javanese text is visible on an iTerm screen, there will be terrible performance degradation, lots of beachballing etc. The more Javanese, the bigger the hang. Anything that's outputting Javanese in real-time can actually make the entire application unusable and you have to force-quit.

Try pasting this into a terminal: (with cat > foo or whatever)

ꦥꦺꦔꦼꦠ꧀ꦠꦤ꧀

꧋ ꦲꦢꦼꦒ꧀ꦒꦶꦁ​ꦩꦱ꧀ꦗꦶꦢ꧀ꦱꦭꦶꦏꦶꦤ꧀​ꦪꦱꦤ꧀ꦤꦶꦥꦸꦤ꧀ꦫꦢꦺꦤ꧀ꦔꦤ꧀ꦠꦺꦤ꧀ꦡꦸꦩꦼꦁꦒꦸꦁ​ꦦꦿꦮꦶꦫꦢꦶꦂꦗ꧈ ꦭꦗꦼꦁ​ꦏꦮꦏꦥ꧀ꦥꦏꦼꦤ꧀ꦏꦁꦒꦺ​ꦥꦂꦭꦸꦤꦶꦁ​ꦆꦱ꧀ꦭꦩ꧀ꦭꦤ꧀ꦩꦸꦱ꧀ꦭꦶꦩꦶꦤ꧀ꦲꦶꦁ​ꦱꦭꦩꦶꦭꦩꦶꦤꦶꦥꦸꦤ꧀​ꦥꦩ꧀ꦧꦶꦏꦏ꧀ꦏꦶꦥꦸꦤ꧀ꦲꦶꦁ​ꦢꦶꦤ꧀ꦠꦼꦤ꧀ꦏꦼꦩꦶꦱ꧀ꦏꦭꦶꦮꦺꦴꦤ꧀ꦠꦁꦒꦭ꧀ꦏꦥꦶꦁ꧇ ꧑꧖꧇ ꦮꦸꦭꦤ꧀ꦗꦸꦩꦢꦶꦭꦮꦭ꧀ꦠꦲꦸꦤ꧀ꦗꦶꦩ꧀ꦩꦮꦭ꧀ ꧑꧘꧘꧕꧇ ꦲꦸꦠꦮꦶ​ꦯꦸꦂꦪ​ꦏꦥꦶꦁ꧇ 21 ꦮꦸꦭꦤ꧀ꦗꦤꦸꦮꦫꦶ 1954 ꦢꦺꦤ꧀ꦤꦶꦁ​ꦫꦢꦺꦤ꧀ꦔꦤ꧀ꦠꦺꦤ꧀ꦡꦸꦩꦼꦁꦒꦸꦁ​ꦦꦿꦮꦶꦫꦢꦶꦂꦗ꧉

ꦏꦠꦿꦁꦔꦤ꧀

꧋ ꦱꦢꦺꦫꦺꦁꦔꦶꦥꦸꦤ꧀ꦩꦱ꧀ꦗꦶꦢ꧀ꦱꦭꦶꦏꦶꦤ꧀ꦏꦒꦫꦥ꧀​ꦱꦩ꧀ꦥꦸꦤ꧀ꦮꦺꦴꦤ꧀ꦠꦼꦤ꧀ꦩꦲꦸꦗꦸꦢ꧀ꦥꦤ꧀ꦝꦼꦩꦺꦤ꧀ꦤꦶꦁ​ꦩꦱ꧀ꦗꦶꦢ꧀​ꦯꦸꦫꦩ꧀ꦧꦶ​ꦱꦲ​ꦥꦭꦩ꧀ꦥꦃꦲꦤ꧀​ꦱꦂꦠ​ꦧꦺꦴꦤ꧀ꦝꦱꦮꦠꦮꦶꦱ꧀​ꦏꦢꦺꦴꦱ꧀ꦠ꧇ ꦮꦼꦝꦶ​ꦒꦩ꧀ꦥꦶꦁ​ꦏꦗꦼꦁ​ꦭꦤ꧀ꦱꦤ꧀ꦤꦺꦱ꧀ꦱꦤ꧀ꦤꦺꦱ꧀ꦱꦶꦥꦸꦤ꧀​
ꦱꦺꦴꦏꦺꦴꦁꦔꦤ꧀ꦱꦏꦶꦁ​ꦥꦫ​ꦩꦸꦱ꧀ꦭꦶꦩꦶꦤ꧀​ꦢꦺꦤ꧀ꦤꦺ​ꦲꦶꦁꦏꦁ​ꦔꦿꦚ꧀ꦕꦁ​ꦱꦲ​ꦔꦮꦠ꧀ꦲꦮꦠ꧀ꦠꦶ​ꦥꦁꦒꦫꦥ꧀ꦥꦶꦥꦸꦤ꧀ꦩꦱ꧀ꦗꦶꦢ꧀​ꦫꦢꦺꦤ꧀ꦔꦧꦺꦲꦶ​ꦕꦺꦴꦤ꧀ꦢꦿꦢꦶꦥꦿꦗ꧈ ꦲꦶꦁꦏꦁ​ꦲꦁꦒꦫꦥ꧀​ꦫꦢꦺꦤ꧀​ꦯꦸꦰꦺꦗ

ꦥꦔꦿꦺꦃꦲꦶꦁꦩꦱ꧀ꦗꦶꦢ꧀ꦱꦭꦶꦏꦶꦤ꧀

ꦥꦔꦂꦰ꧇ ꦫꦢꦺꦤ꧀ꦲꦗꦶꦩ꦳ꦸꦃꦏ꦳ꦩ꦳ꦢ꧀‌ꦔꦢ꧀ꦤꦤ꧀
ꦥꦤꦶꦠꦿ꧇ ꦫꦢꦺꦤ꧀ꦔꦧꦺꦲꦶꦕꦺꦴꦤ꧀ꦢꦿꦢꦶꦥꦿꦗ

Required information for bugs. I probably can't help you unless you include this:

• iTerm2 version: 2.9.20160313
• OS version: 10.11.3
• Attach ~/Library/Preferences/com.googlecode.iterm2.plist here: com.googlecode.iterm2.plist
• Attach a debug log (https://iterm2.com/debuglog): debuglog.txt

I suspect the fix to #3568 (closed) will also fix this.

Milestone changed to Feature Complete 3.1

I've done everything possible to improve performance. Apple's text drawing is just slow :(

closed

Thanks for looking into it. I'll talk to the CoreText folks.