Is FTL compatible with Windows 8.1? It runs at something like 2 frames a second on my PC. I have tried running it in various compatibility modes with no success. I do have an old PC but I just bought Geometry Wars 3 and that runs fine.
Hard to believe this machine can't handle a 2D game.

Any info or suggestions welcomed.

Win 8.1 has nothing to do with that, it's compatible. Although being in 2D, FTL is pretty CPU and graphics card demanding game. What are your specs?

It could be a driver issue. Update your graphic card's drivers. The problem is, AMD and Nvidia often don't offer proper Windows 8 drivers for older cards and graphic chips. You might be more lucky trying community drivers or betas instead of the official ones, but I don't know of any optimized for Win 8.1. If the official drivers and betas don't work you can give the older Omega Drivers a chance (http://www.omegadrivers.net/).

..and make sure, DirectX is properly installed.
Install this to get all older components:
http://www.microsoft.com/en-us/download/details.aspx?id=8109 (Extract to a separate folder and run dxsetup.exe)
and afterwards this to update everything if necessary:
http://www.microsoft.com/en-us/download/details.aspx?id=35

In case you're playing in windowed mode, the game seems to run faster in fullscreen.

I'm sure that you're right but the minimum specs listed on GOG are pretty minimal.

This was the solution from Steam forums:

I had the same issue and resolved it by doing the following:

1. Use the uninstall option of the catalyst driver package that you linked to remove all AMD components from the computer.

2. Use the install option of the catalyst driver package to do an Express install of the driver.

When I tried to install the driver without uninstalling the AMD components first I was also getting the "Driver Install: the specified driver package was not installed for matching devices" message. When I installed the driver after uninstalling the AMD components I got a different message that indicated that some warnings were triggered but the driver was installed successfully.

3. Change the display adaptor to use the new driver:
a. Navigate to Going to Control Panel > Hardware and Sound > Devices and Printers > Device Manager > Display Adaptors > ATI Radeon HD 4800 Series.
b. Right-click on "ATI Radeon HD 4800 Series" and open "Properties".
c. Click on the "Driver" tab and click on "Update Driver".
d. Select "Browse My Computer for Driver Software".
e. Select "Let me pick from a list of device drivers on my computer".
f. Select "ATI Radeon HD 4800 Series" (the one without "Microsoft Corporation...").
g. Click "Next". The driver should start installing and your screen should filcker a few times.
h. Click "Close".


Long story short, it was using the crappy Windows driver instead of the ATI/AMD one.

Thanks for the feedback. So switching from Windows standard driver to AMD's current driver actually did the trick for you and FTL runs fine now, doesn't it?