Is there a way to streamline that loading time?
Is it just my impression that it takes longer?
It may not be just an impression - but loading time depends on the browser and even different components of your PC, virus scanners, connection etc.
Joseph asked same kind of a question some time ago and I tested various settings trying to load editor faster - and the result was that problem did not seem to be in editor code itself - editor just happens to popup last after other code has been rendered.
Yes, I agree and in my tests (in the same post) cache did have some effect but it did not explain everything. There are so many things that can have influence that I am glad to leave such things for performance experts...
Furthermore - Firefox 3.6.10 does not yet use direct2d/directwrite hardware acceleration by default so it is very likely that your PC / Firefox does not get any benefit of hardware acceleration... see for example