I've seen this claim several times in this thread now. Having used Fastmail since 2013, how is it blazingly fast since its UI will randomly perform a full reloa

I've seen this claim several times in this thread now. Having used Fastmail since 2013, how is it blazingly fast since its UI will randomly perform a full reload when you switch back to its tab? It happens multiple times a day. The last time I've had Gmail suddenly decide to reload the page the moment I need to use it? Never.