GTK2 performance on Sparc Solaris

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Hi, I'm running GTK2 applications on Sparc Solaris. I noticed that sometime after GTK2 version 2.6, the performance got much worse, i.e. things are rendered very slowly. I suspect two main reasons for this are:

1. Sun's Xserver does not implement Render extension
2. GTK2 switched to cairo, which many affect performance

My question is: are there any options to disable unnecessary "eye candy" in GTK2 or to revert to the old behaviour (i.e. not relying on cairo, etc)? Currently I'm running gtk2+-2.8.12, any suggestions on how to improve speed with Sun Xserver?

P.S. I thought about replacing gtk2+-2.8.12 with gtk2+-2.6.x, but would like to find out if there is a a way to speed things up with the the current version, and why there is a such a dramatic performance drop.