Just wanted to share this with you all....
I have been running all my PT sites on a Windows 2008 R2 platform using mostly PHP v5.2 with a couple of sites testing 5.3 and 5.4. The PHP install is integrated in to Windows Platform Installer so it's always a little behind the times! Anyway, 5.6 was released to this installer recently so I whacked it on my server. Wow - massive speed boost! I haven't actually moved any of my front ends across but all my scripted/automated back end processes are using it, such as importing etc.
I seriously recommend trying this version out if you can as I think you'll be pleasantly surprised!
Thanks for the note, Keeop!