The performance option lets you slide between "low performance" and "high performance".
There is no indication what this does or what performance it is asking.
Is this for selecting the performance of you machine? Is this for selecting the performance of YACReader?
If it is asking for the machine performance, it should make that clear.
If it is asking for the performance that YACReader should run with, shouldn't it always run with the highest performance, if it apparently doesn't have any other effect?

It should definitely be more clear what this option does.

I do not remember the exact details behind this setting, but you choose low performance in a low performant machine...

Things like vsync, anti aliasing etc are enabled disabled under the hood. The idea was to hide all these advance setting from the user and make setting this up as easier as possible.

If I recall correctly that option sets the texture sizes for the flow.