I use Windows 8 and when clicking on a krarec file generated by Krita, my system doesn't know how to open it. Do I need a separate program to view it?

Unless I'm mistaken

Open krita
Go to tools > Macros > Open and play
Select file in dialog

it actually looks like we broke this feature in the 2.8 release And nobody noticed!

Oh, I hope you bring it back! It sounds like a very interesting, educational, and unique feature.

Yes... Found the bug, it was a simple error in the code to open a file name that crept in when we tried to enable the native Windows file dialog. Will be fixed in 2.8.1 on Windows.

Hopefully this does not come off as complaining (because is a wonderful program) but just in case this input is helpful, 2.8 seems to run pretty slow on my windows 8 laptop. Much slower when compared with Photoshop.

Did you enable opengl in the settings dialog?

What is GL? I did just click it after reading your post, but it did not appear to speed anything up. If I am zoomed out while painting with a large brush, the paint trails behind the pen a bit. It also takes about a minute to open the document. (It takes seconds in photoshop on the same computer.)

OpenGL usually speeds up rendering the image to the screen. If that doesn't make a difference for you, it's the actual brush calculations that are expensive. We use SSE2, AVX and AVX2 on systems that support that, but if your system is older or you are using a 32 bits version of Windows and Krita, Krita will probably be slower than Photoshop.

We're optimizing our code all the time, but I guess there will always be a difference...