http://bugs.winehq.org/show_bug.cgi?id=14438
--- Comment #16 from Christoph Korn c_korn@gmx.de 2009-01-31 11:59:43 --- Created an attachment (id=19127) --> (http://bugs.winehq.org/attachment.cgi?id=19127) registry file to use opengl as DirectDrawRenderer
This registry file fixed the bug for me.
Now the game runs at normal speed also when the X colour depth is 24bit.