Haml currently compiles 128 ERB templates during bootup as a result of #def_static_method. This takes roughly half a second on my machine.
By using Erubis' TinyRuby rather than ERB to do the parsing, this takes about 1/3rd as much time. If Erubis is not available, Haml will fall back to ERB.
Use Erubis for parsing static method bodies if available
Use TinyRuby rather than Eruby for static method parsing.
I think it should be included to 3.2 release.
Sorry for the long delay in applying this, I'm merging it into master and will get it into 3.2.0.