I have not experienced anything as such recently, but it may be your internet connection, router, area you live in, etc. The latter is less likely, but still a possibility (rather slim). Perhaps try rebooting Gmail and/or check other sites and see if they are working well and smoothly. If so, it is a problem with Gmail solely and you should be able to troubleshoot it rather easily. If not, then you may need to restart your computer/phone/tablet. If that doesn't work, check any and all connections to those devices (that supplies it with stuff like wifi, I do not mean speakers and the sort). If none of the above help, I would advice getting your device checked by a professional.
Hope I was of any help at all,
Alexander
