Nasty bug after iOS 11.2.6 on iPhone 7

So I knew about the phenomenon that Apple deliberately slows down iPhones because of battery. But after iOS 11.2.6 the performance of my device drastically decreased. E.g. when I'm typing my phone lags every 5 seconds and some swipes or clicks take several seconds. Weird thing is that in general use (searching on browser, reading the news) there's no difference but especially when typing it's just not use-able. Anything I can try before going to an Apple store?