Desktop App Lag - typing msgs, switching channels, etc

Try these ideas.

The issue could be with

Teams itself (Unlikely)

Your firewall

Your Internet service provider speed

Your Internet service packet loss (This is a very common cause)

Your WiFi

Your WiFi channel

So firstly what can you do.

Run a speed test. If > 20 mbps you're all good. If below you have an issue with your ISP or wifi signal. 

Add an exception for teams on your firewall

Check for packet loss. Use command and enter ping http://www.facebook.com -t. Check for any timeouts as this is packet loss. Google how to do this. 

Packet loss can have many reasons why it occurs so if you notice timeouts look it up. One potential cause is wifi issues. These can include too many people using the one channel, an underperforming network card etc...

A solution for improving Wi-Fi is to get a Wi-Fi adapter. It's basically an antenna to improve your PC's ability to get WiFi reliably. 

If this all fails log into your router settings. Change the WiFi channel. Google how to do this. 

Whilst in your router settings consider port forwarding any ports required for teams

I know I haven't gotten into detail here. Google how to do things if you don't know how.