Ok Glad I cold help, please hit the thumbs up on my post and also click on this is the solution button as this improves my status on the VM Community.
As for your specs I have used worse machines and can say confidently that they would defiantly not be a cause for concern although I would recommend the CPU upgrade like you said Overtime quicker speeds will cause issues here and will become a bottleneck if you do get gigabit later on.
The reason I suggest the app is because I know its more accurate than a web browser as at the moment only high end machines like mine with I9's and 64GB of RAM which as you can expect the result to be similar although never as accurate but even I get issues there.
As I'm on the M100 tier I know what I can get.
But I have good a gigabit FTTP connection as well as virgin media M100 at another location with Orange FR which performs much better with Pings of 0-1 and maxing out over the gigabit connection as obviously you cant get true gigabit over that connection type. but I have used web browsers on that connection and noticed that my CPU usage goes right up but when in the speed test app I get what I expect and generally my CPU is under no real strain.
Below I have attached a graph of the virgin speeds product graph and what you have described as the speed your getting is excellent and is what I would expect for your tier of service.
If you have any more issues feel free to send me a message on then forum email.