Your best option, after having read the comments you provided, is to put a new branch circuit in for the Microwave, even though it is more difficult in your particular circumstance.  The microwave should have a 20amp circuit, because it runs at over 13 Amps.  14AWG wire is rated for 15 Amps, but for continuous loads the rating drops to 12 Amps (80 percent of non-continuous per NEC 210.20(A)).  You should also protect this new circuit with an GFCI outlet, especially if it is near a sink/water. Leave the 14 AWG wires connected in the back of the box so they feed the other outlets.

What to do with old connections when moving outlet to dedicated circuit?
There are lots of different online performance tests: 


Google PageSpeed Insights 
iWebTool Speed Test
AlertFox Page Load Time 
WebPageTest


Also there are several desktop/client software such as: 


ping tool
YSlow
Firebug's Net console
Fiddler
Http Watch


I just want to decide if my hosting provider has a good enough performance or if I need to switch my hosting to another provider.

So, which tool should I use to compare my hosting provider with other hosting providers?
