When doing screen recording, I can get a frame rate of maybe 15 frames per second for the full screen on my 1080p monitor using the XVID codec. I can increase the speed a bit by recording a region, changing screen modes, and tweaking other settings, but I'm curious what hardware upgrades might give me the biggest bang for my buck.

My PC is budget, but modern...

• Athlon 2 X4 645 (3.1GHz, quad core, limited cache) processor.
• 4GB single channel DDR3 1066 RAM.
• ASRock motherboard with NVidia GeForce 7025/nForce 630a Chipset.
• ATI Radeon HD 5450 graphics card - 512MB on board, not configured to steal system RAM.

I dual-boot Windows XP and Windows 7. For the moment, XP is my bigger performance concern as it's still my getting-things-done O/S as opposed to my browser-host O/S.

My goal is to make a few programming-related tutorials. For a lot of that I don't need screen recording - I can make up some slides, record audio with the PC switched off, yada yada. When I do need screen recording, I'll mostly be recording Notepad++, Visual Studio or a command prompt. Occasionally, I may be recording some kind of graphics or diagram program and using my pre-Bamboo cheap Wacom tablet - I have the CS2 versions of Photoshop and Illustrator, but I'd much more likely be using Microsoft Paint. Basically, what I'll be recording won't be making huge demands on the machine - but recording a fair number of pixels (720p preferred) will be useful.

What's particularly wierd - not so long ago I still had a five-year-old Pentium 4 based PC. And (with the same 1080p monitor) it could record at not far from the same frame rate. So clearly the performance issues are more subtle than just throw-money-at-it.

My first guess would be that the main bottleneck is the bandwidth for transferring data to/from the graphics card. Is that likely to be correct?

• In support of that, see this [Radeon HD 5450 review][1] - the memory bandwidth is only 12.8 GB/s. If you can't get data out of graphics memory quickly, you can't transfer it back to the system memory quickly. Apparently, that's slower than some top-end cards in 2002.