Over the past few days, there have been reports on this form of a general network issue in certain areas. You will want to do a network check according to the above advice (coverage page but click "check network" to ensure you're not debugging an issue which is already known).
"Check network" shows an issue in my area in the South East which is probably a continuation of the same report from yesterday.
Once your loaded ping is below 600 ms, things should be more normal. Beware that bandwidth checks will consume data (50 MB to at most around 200 MB) so do not do them too often if you have limited data.
