Oh yes, indeed. I've finally found this font. Probably it will be worth consider to replace this currently used everywhere Ubuntu Mono Bold with Kabel family. I only hope that font's license is compatible somehow with our little project... But firstly I have to do some tests with that font.
Different techniques work differently on different hardware. I added something that normally works well if used correctly. But there are other aspects one might want to take into account. CPU->GPU transfer, driver overhead, some internal optimizations, etc.
Buffer object streaming was implemented on GL33 engine. But UI rendering (especially text rendering) is poorly optimized. I'm thinking of implementing something aka glBegin...glEnd to speed it up.
Most of my GPUs were always Nvidia's. I had only Radeon 7500 and 9550 in my whole life. Both utylized so I have no access to them now to make some tests with my second computer with AGP.