My MacBook Air (13 inch, mid 2012) started to be very sluggish recently: every action occurs after a visible delay (starting app, loading youtube in a browser, startup, etc). Besides, Newer Tech battery that I installed in mid-December died (macOS thinks I don't have a battery at all).

I ran Geekbench 4 on my machine after closing other apps (I actually left Dropbox and pcloud running, but closed Safari and itunes). It turned out that my CPU score in Geekbench 4 is three times less than reported by another user with exactly same machine):

https://browser.geekbench.com/v4/cpu/compare/6882608?baseline=6473068

The only difference I can see is that I use macOS 10.13.3 while another user uses macOS 10.13.2. Can poor performance of my MacBook be attributed only to the difference in macOS version?