Slow RPi

I have three Pi3s running osmc. I noticed one seems a little slower and I see the gold lightening bolt appears in the right upper corner more than the others. I switched out power supplies and micro USB cord - no change. I purchased a new Micro-SD card and did a fresh install and a restore of the backup from my other pi which seems to be the fastest. This seems to help with speed. My question is has anyone noticed variability in performance of various Pi’s? Also wondering if SD might have been corrupted and it be fixed with reformat or is it toast? Thanks

Power Supply is your problem. Replacing a bad power supply with another bad power supply doesn’t help. Get yourself a quality supply like this one: Raspberry Pi Power Supply 2.5A - OSMC

I’m using an old Apple iPhone cube - these have worked well on my other Pis.

Get a real power supply, NOT a phone charger.