Freezes in chrome and safari

[Sas]

I have noticed that the interface is very sluggish and slow to load in Chrome (whether in incognito or regular mode, Version 58.0.3029.110 [64-bit] ) and causes a CPU spike and freeze on Safari (in either private or regular mode, Version 10.1 [12603.1.30.0.34]). These problems do not happen at all on Firefox (53.0.2 [64-bit]). I am on MacOS 10.12.4 (16E195) and my router is RT-AC68U and I am using the latest stable firmware (380.65_4). There is nothing at all in the error console in Chrome except a warning (if I turn on Verbose) about "Parser was blocked due to document.write(<script>)". Any ideas what could be causing these problems? Thanks!