If you've been using Safari for ages and just used Chrome for the first time on that machine, it could be Safari's cache & other temp files have just grown very big and clunky. Did you try to clear these caches in Safari already? Would be surprised if with clean cache there is much noticeable performance difference between the two.
Besides, do you have any ad-blockers installed in Chrome but not in Safari? That could speed up loading times a lot on ad-heavy sites, but then the ad-blocker makes the difference.