Hi, after the upgrade to Yosemite Safari 8 is really slow to load pages. Takes 10-15 sec to load webpages, when I use chrome it takes under 1 sec to load the same page. On Mavericks Safari was running smooth. The iMac is an late 2013 27", 1TB FusionDrive, 16GB RAM and the i5 CPU.
On my MBPr also with Yosemite Safari is running as normal, fast and smooth.
Any pointers on what i can to do fix this? And are other people experiencing the same problem?
My experience has been that different Macs run differently and the same Mac runs differently at different times.
I doubt it is a memory problem since with 16 Gigs of RAM, you certainly have enough memory.
One problem may be WIFI interference from other devices. Have you tried both Macs at the same time? Is there interference on the channel you are on? (I like WiFi Explorer, but there are a number of good apps to help you see what other devices may be interfering.) Try changing the Channel. Also look at the TX Rate, which often fluctuates. Is it as high as it should be?
Another problem may be the websites you visit. Have you tried visiting the same website on both Macs. If the same website loads differently on the two Macs, then clearly you have a problem that may or may not be Yosemite related. Many websites are not really Safari friendly although more and more are becoming so. Try comparing response time on the same website.
Try resetting the NVRAM and the SMC.
In addition to what I have already mentioned, and in fact before resetting NVRAM and SMC, you should repair permissions and also you should do a Safe Boot. The latter cleans some caches, which also may be the source of the problem.
Finally, since your iMac is late 2013, I assume you have Apple Care. Try calling them and see what they say.