The boot time is an obvious victim of OA for me, I've resigned long time ago to the fact that my boot will increase noticeably. I have never experienced any similar issues with Outpost, privateFirewall, Comodo, Kaspersky, etc.
Never thought about joining the others who reported this to Tall Emu & Emsisoft, since that debate has been going on and on for years, without any reasonable progress.
According to Soluto, OA takes 20-24 seconds and has a disk load of 3 - 3.5 GB on boot.
I was looking forward to OA 6 fixing the issue, and for a moment I thought they've made a massive breakthrough - restarting after downloading the OA Free upgrade went in a flash, only to be disappointed that it's still OA 5 - don't really know what happened there...
And then be disappointed even more once it upgraded properly and I had to face the protracted boot again...
Another improvement I was looking forward to was the Chrome and Sandboxie compatibility fixes. Browsing with Chrome sandboxed worked, a bit too slow, though, so I promptly added Chrome back to the exclusions list in OA.
All in all, this has been an "even Steven" release for me, a case of nothing gained, nothing lost...