[KevinH]

He is not being rude. You reported a bug, that can not be duplicated by all others. The bug may be either in Qt (the webengine toolkit used by Sigil) or in your video driver, or just specific to your system.

We then point you at turning off the gpu via Sigil preferences so you can test if the driver or qt may be at fault, but instead of trying that and reporting back whether it fixed the issue for you, all you said is you tried it and then did not like it.

Once pushed for more you came up with a frame rate measure that is effectively meaningless for an epub. Preview is only updated when receiving a signal that something has been edited in the epub or scrolling is needed. And that has its own timer to prevent unnecessary duplicative updates. This is not a video game. Any lag is due to your system io once the signal a scroll or edit has been done and the timer runs out.

When again pushed for more info on how you are measuring frame rate in a meaningful way you then admit it was by eye.

You finally did add that the memory issue went away when you disabled the gpu.

Then you wonder why we are upset?

Please try updating your gpu video driver to the latest version. Qt/Chrome only works for the most recent video graphics cards. That is why we added the Preference to disable its use so that you can continue to use Sigil normally.