You might recall running UAE on an old 200Mhz Pentium processor, and wonder how it is possible that performance is even a topic in 2012 🙂 The emulation accuracy in modern UAE emulators is much better than it was10-15 years ago, and this incrased accuracy comes at the cost of requiring more powerful computers.
Emulating the Amiga 1200 is especially demanding, since the CPU is clocked twice as high as the CPU Amiga 500, and the emulator spends most of its time emulating the CPU.
Here are some tweaks you can to do increase the performance of FS-UAE.
Some desktop environments under Linux causes bad performance, usually problems caused by compositing window managers. Some workarounds are suggested further down (“Performance Problems with Ubuntu / Unity”).
Lowering the Accuracy
If your computer is struggling with emulation at 100% speed, the easiest way to get better performance is to lower the accuracy:
accuracy = 0
This will turn off cycle-exact mode, but it will also be less compatible. Though, for many games / applications, it will not matter. You can also set it to -1 for even more performance.
FS-UAE Launcher has a drop-down box to the right of the Amiga model selector where you can lower the accuracy.
Disabling Video Sync
FS-UAE will usually have higher performance with video sync turned off:
video_sync = off
Note for Linux users: Many compositing window managers have performance problems when running OpenGL apps syncing to vblank. Common symptoms include half frame rate. In this case, you can either use the above option, or run FS-UAE in full-screen (which usually solves the problem, but Unity/Ubuntu may still have performance problems), or turn off compositing.
Reducing the Color Depth
FS-UAE can use less color depth in the internal video buffers as well as in the textures uploaded to the video card. For slower/older computers, this can give a nice speed boost:
video_format = rgb565
(This option will also automatically set texture_format = rgb5).
Use the Slowest Amiga Needed for the Job
Don’t emulate an Amiga 1200 if an Amiga 500 or an Amiga 600 will do. The CPU in Amiga 1200 is twice as fast as the one in Amiga 1000/500/500+/600, and you need a much more powerful computer to emulate A1200 at highest accuracy.
For example, many people use Amiga 1200 settings when running WHDLoad-installed games. But for most games, an Amiga 600 with Kickstart 2.0 will work equally well (or better), but will require a lot less resources to emulate.
Avoid Unnecessary Options
FS-UAE requires more CPU performance when options such as scanlines are enabled. GPU performance is also affect when using shaders and full-scene anti-aliasing.
Performance Problems with Ubuntu / Unity
When running in full-screen mode, the performance may be bad when running in the Unity desktop on Ubuntu. Enabling “Unredirect Fullscreen Windows” in CompizConfig Settings Manager may fix this problem, see the following pages for more information:
(The fullscreen issue may be fixed in recent versions of Ubuntu).
Unity also causes performance problems in windowed mode due to the compositing manager not playing nice with OpenGL apps syncing to vblank (at least with the binary nVIDIA drivers). Set the following option to get better performance under Unity if you are affected:
video_sync = off
Or run it in fullscreen mode instead. Another desktop environment without compositing is also a good choice 🙂