You can suspend tabs in SJ using The Great Suspender extension, not natively.I have preferred CENT BROWSER over Slimjet coz it can suspend unused tabs and saves me lots of resources also lazy loading... Is it available in Slimjet yet !!
I used Opera since v 3.62, with a couple of breaks for Firefox and Chrome when they first came out. But opera's change a couple of years ago lost them a lot of good will. Last I checked, which admittedly was quite a while ago, the new browser still wouldn't let you spec a default search engine that wasn't in their preferred group. They said they were protecting us from search hijacks. Unbelievable, literally.
I've tried quite a few browsers, and consider SJ to be the best. I use it on both Windows and Linux. Maxthon's Nitro was a very interesting experiment, but not practical.