dawge, I noticed while I was ingame the other night looking through the options settings that the tooltip font size can be changed from within options.
Very helpfully now that I am in work I have forgotten exactly which setting and where in options but if you have look around in the display settings options somewhere I can assure you that you will find what you are lookiing for.
I played around with it and on the max setting the tooltip was taking up a good 25% of my screen, it was massive
