On Mon, 24 Jan 2011, Sheldon Simms wrote:
50% is maximum load, not typical. The main reason it consumes so much CPU is that the display routine is ideally called after every emulated instruction. You can save CPU at the cost a loss of emulation accuracy by calling it less often.
If I recall correctly, the rewritten video core in Dapple called the display routine once every 65 emulated 65SC02 cycles, covering a single scanline at a time.
Whatever it did, it did well - within the limit that it was drawing to a 320x200 buffer (as it was the only way we could get reasonable speed at the time). I suppose if Holger Picker's line by line strategy and your actual emulation were combined, the results would be utterly mindblowing.
How much overhead does SDL have? I'd recommend any new emus are best done to target a multi-OS library if possible.
-uso.