The Google Chrome browser is known to be memory intensive. This may be a situation where your MacBook Air does not have enough RAM AND may be running too many other apps, that Chrome is causing your Mac to "slow down" to swap some of those apps to the system drive.
Since we don't have much information on your Mac, I suggest that you run an EtreCheck report, and optionally, post it here if you need assistance with interpreting its result. EtreCheck is a diagnostics tool, created by a valued forum member, that greatly aides in troubleshooting difficult Mac issues ... like the cause for this one.
Ref: Using EtreCheck to Troubleshoot Potential… - Apple Community