Various minor speed-ups

[Dimitrios Apostolou]

Hello list,

the followup patches are a selection of minor changes introduced in 
various times during my GSOC project. They mostly are simple or
not that important to be posted alone, so I'll post them alltogether under 
this thread. Nevertheless they have been carefully selected from a pool of 
other changes and they are the ones that *do* offer some (minor) speed 
improvement, and have the least impact on memory usage, if at all.

They have all been tested on x86_64, some also on i386. For production 
builds I have seen no regression introduced.


Thanks,
Dimitris