Veggieseasons sample drops frames while scrolling

[kobutri]

I noticed that the veggieseasons sample app drops below 60fps while scrolling through the veggies on the home screen.
I get an average of around 20ms/frame GPU time and max GPU time of around 30 ms/frame.
So it only runs about 50fps, which seems like a small deviation but on a fixed refresh display it leads to micro stuttering.

Test Setup:

Flutter 1.7.4 release build.
I turned on the performance overlay by adding to showPerformanceOverlay: true to the CupertinoApp widget.
I testest both on a Galaxy S8 with Android 9.0
and a iPad 6th generation running iOS 12.3.1
Both had similar frame times.

I know that these are not fastest devices but it is just a simple list after all and I would expect scrolling to be smooth.

[kobutri]

I've done some more testing and it's probably obvious but, disabling the blur CupertinoSliverNavigationBar by selecting an opaque color solves the problem, but is not really what I want.
I would assume that the blur functionality in Skia is already well optimized, but then again, it isn't a problem in native iOS apps.

[ericmartineau]

The scrolling was smooth in 1.5.x and has since regressed.
flutter/flutter#36064

As noted in the other issue, I've tested this with the veggieseasons app specifically

[ericmartineau]

Video with performance overlay of the two versions:

Screencast v.1.7.8+hotfix.4 (youtube)
Screencast v.1.5.8 (youtube)

[RedBrogdon]

CC: @HansMuller

Clearly we needed our own issue tracker for the samples for a while now.

I don't have an iOS hardware device on me today, but I'll try to verify if this problem still exists with the current SDK early next week.

[ericwindmill]

Given that Flutter on iOS uses an entirely new rendering engine today, I'm closing this comment as outdated.