I'm not certain how you intended that statement, so I may be stating stuff you already know. But to get faster performance out of the system as a whole, without causing video glitches, wouldn't you want more wait states for the video RAM?
Presumably, there's a fixed number of nanoseconds the VRAM needs to respond. As the clock speed goes up, the length of a clock cycle goes down. So to match a fixed period, like RAM access, as the clock speed goes up, number of wait states need to go up so that the product of clock period and wait states remains a constant.
Ideally we don't want to wait longer than we have to, since that just makes all graphics slower. Anyway, it turns out that even with all the wait states I can turn on, it's still not waiting long enough, so there are eventually graphics glitches at 50MHz. Seems okay at 48Mhz, though!
I've been meaning to document my oscillator socket, so here's some pics that should make it fairly clear:
Here's the socket I started with (p/n 1107741-E but not really necessary, probably any similar socket will work) and some pins:

Add the extra pins and clip the ones on the ends:

Using some bits of wire, connect these pins:

Then solder it on top of the oscillator on the board:

View from the other side:

And with the oscillator:

Make sure you get the orientation correct!
I'll also stick these pics in my github repo for this project.