I recently got an S9 on contract 2 days ago, and have noticed it is very slow to load certain things(insta posts, reddit, facebook) sometimes. I'll turn wifi off and it'll load perfectly normal on data. I've used both 2.4g and 5g wifi and get the same results. It's not always an issue, but it's been happening frequently. I made the switch from an S6 and the S6 has no issues on wifi. I've researched this issue, and seen that it's a common problem. Is my phone simply defective? I have a 15 day window to return/exchange the phone, and am unsure if I should try another S9 or simply get another phone. I've factory reset the phone twice and nothing has worked.
@craniaxxstuo: Have you tried connecting to another WiFi router to see if the problem persists? If it does then try going to Settings > General Management > Reset > Reset Network Settings > Reset Settings to see if this helps.