1-3% stale shares excellent mining performance. If you have more than 5%, then a bad internet connection may be the cause.
I also have 2-3% stale shares, when there are problems with the Internet, this indicator increases.
Mine further and don't waste time on this question.
You will need to pay for a faster internet connection and look for mining pools with the lowest ping.
You will spend a lot of time and increase expenses, the profit will be minimal. I don’t want to waste my time on this, and I don’t have the opportunity to improve the speed of the Internet connection, because I use a 4g modem.