2 Questions - Refreshing Cached pages without crawler + Performance issues

Hi there,

for a while i am using boost i am happy with it. For weeks i try to figure out which settings are optimal for my site and i have got two questions even through i read the documentation carefully.

"Expire content on cron only if the sites content has changed." Does the same goes for views or panels, or only with nodes which makes more sense to me. And whats happening with nodes which were commented? Does they get into the expired database table?

Issue Number two: Does the available boost settings allow refreshring pages without running the boost crawler? I already shrinked the settings, but it eats perfomance which i better want to give to my authenticated users. Maybe you have some tweaking tipps for me so that i dont have to do without the boost-crawler. I attached a CPU Usage screenshot.

I am on a ubuntu root server with 4gb ram and 4 x 2,4 GHz

I tried a lot but cant figure it out. I hope to get some Informations.

Thank you.