Hi!

REASON 1 ANSWER:
Few of us Evangelists were already discussing the return of PAUSE button with avast! team and they are working on it. The request for it was rather huge so, it’ll return (I just can’t say when exactly). We also talked about additional statistics (like last scanned file, scan speed in MB/s etc), but we have no info on that yet. Hopefully it’ll return as well.

REASON 2 ANSWER:
Hm, there shouldn’t be any performance difference. In fact, new avast! 17 should be actually faster because it’s employing improved scanning mechanism. I also don’t seem to notice any difference on my 2 low end systems (one has AMD E-450, the other has Atom X5 Z8300). Not sure what could be the factor in your case. Hm.

If you go into “Run Full Virus Scan” settings (small gear button in the scan’s button), Performance section, select “Speed up scanning by using persistent cache”. This should significantly speed up the scanning while not really affecting scan or detection quality. What this setting does is just skipping of safe files (that have intact digital signature or are whitelisted by avast!). Real-time shields already use this by default, full system scan doesn’t for some reason. Hope this helps a bit.