Everyone is slow when he/she first starts the job. Tell them you

catch up the speed as time goes by. Don't give up yet until you find another good one.

Your supervisor is obviously a *****! There is absolutely no doubt about it.

I had a similar situation 5 yrs ago.  When I first started at that company, everyone in the accounting dept hated the manager and of course she was a very horrible psycho and she complainted to the CFO I was slow. I told the CFO I would pick up the speed later cuz I needed to focus on accuracy first. I had been there for two weeks or so.

I was so mad and talked to my co-workers and they all told me to ignore that psycho.  After two months, I found another job, left my resignation letter to HR on the pay day and left.

Later on, my ex-collegue told me that psycho actually liked my work after one month but she didn't know why I just left without telling anyone.

The job market is tough, take your time and find a good one! No one want to work with *****es!