I've just got my raspberry pi and got it working. I downloaded raspbian and got it to boot. After a while problems started to show up, I'm starting to get the lightning bolt that I think indicates for undervoltage and the psu at this time is a Samsung s5 charger 5V, 2A and no quick charge. So I changed it to an htc 5,3V and 2A, it started good with no undervoltage icon anymore but after a while my raspberry started to lag badly really bad so i unplugged the cable. So now when I'm using my pi I run it on a Apple ipad air charger 5,1V and 2,1A and it's still showing me the undervoltage symbol when it runs over 40%cpu load. Is it the cable that im using that is bad or is it something else.
I also get problems with starting up a program. Everytime when I start up chromium or python the cpu usage goes up to 70% and then it goes back to normal. Everytime i search on chromium it also do this. But when i run a video in youtube it stays at 20%. Any clue whats wrong?
Thanks in advance