Does your Gmail email show up only every 10-15 minutes? Is Gmail slow? Do you have delays in getting your Gmail email?
This happens if you’re using POP3 server for your email and Gmail to read your email. Google checks POP3 servers only every 10-15 minutes (or even 30 minutes). So someone sends you an email and it takes forever to show up. It’s a Google problem.
There’s a solution. Daniel Slaughter’s POP3 Checker forces Google to check the POP3 server. It works in both Chrome and Firefox. It’s easy to install. It uses TamperMonkey (also easy to install).
I suggest you make a donation ($1-5); this lets you set it to check email every few minutes.