Slow rendering after upgrading to 0.6

[snylonue]

• platform: win10 19043
• hardware: i5-7300hq and gtx 1050

I just upgraded iced to 0.6 in my tool written last year. I resolved the compile errors and run it in release mode and found it much slower than the older version (You can compare ec98009 and 9845005).

Is there any work I need to do when migrating?