GtkGLExt+Haskell program running much slower on Windows than on Linux

I have a Haskell program that uses Gtk/GtkGLExt and runs fine on Linux (up-to-date Arch and newest Ubuntu bot开发者_如何学Pythonh, all Haskell libraries up-to-date, using newest 6.* GHC).

However, when I compiled and ran the same program on Windows 7, the GUI is so slow it's almost unusable. This slowness persists even when the rest of the program (usually number-crunching in the background) sits idle.

What is most perplexing is this: once out of about ten times, when run, the GUI will be as responsive as it is on Linux. No other regularities have been noticed.

To run the Windows version, I've had to compile the newest FreeType and FTGL libraries. Because of the "once-in-a-blue-moon-runs-fine" behaviour described above, I tend to think I made no errors here.

Compiling with -threaded or not, and running on more than one core makes no difference.

Has anyone dealt with this behaviour before? Is there something obvious I might be missing?

I'll gladly give more information if I haven't given enough - I simply don't know what else to tell at the moment.

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The one who deserves an accepted answer here is really pechenie.

This is gtkglext's fault. Disable desktop composition under the compatibility options when running the program. This will make the problem go away.

There's a potential fix at this link: http://old.nabble.com/gtkglext-+-windows-7-td24190185.html