Why is my replacement battery slowing down my system?

I purchased and installed a replacement battery for a 9343/9350 XPS 13. The system doesn’t love the new battery - it keeps insisting it’s drained when it’s not and tries to shut down, which I fixed by removing the automatic shutdown option. The larger issue is that the battery seems to be causing all sorts of system issues - it’s running incredibly slow, and recently locked me out of windows altogether, forcing a complete reinstall. I’ve now replaced the old battery and the system is running fine again. Can anyone suggest a fix so I can use the new battery I paid for?