After updating to Catalina , while trying some specific websites I am facing the lag issue in Safari, Firefox, Chrome Browsers. Example while browsing https://apkproz.com ,https://reddit.com, https://facebook.com I am getting too much lag.
I checked my Memory(RAM) usage is normal, Sometimes I am getting the WindowsServer process is consuming more CPU.
Is it related to Catalina OS or something else?
The fact that it is affecting all three browsers could be something else on your system in conflict (e.g anti-virus product, streaming video stealing bandwidth, etc.), or a temporary factor between your router, the ISP, and Internet infrastructure.
I would shutdown the Mac, and any NAS server. Power off your router, and then the ISP modem. Wait ten minutes, and then reapply power in reverse device order.
I have Catalina 10.15.2 installed and observed no change in network performance from what was experienced on Mojave. Using Safari 13.0.4, and Firefox 71.
System lags while Browsing Internet after Catalina update
