Well, I don't know what it can be in your case, but I did the upgrade too and so far I am happy with it.
I did the upgrade from win 8.1 not win 7. I will keep win 7 still for a while longer.

Hi Dave. I upgraded my Dell Windows 8.1 tablet to Windows 10 recently. I had a lot of problems the first week and almost switched back to 8.1. Now I am quite used to Windows 10. There are still some bugs Microsoft needs to work out. However, I'll stick with Windows 10. I'm beginning to really like it. To answer your question, its probably a combination of all three (although, without seeing your specific configuration, there's no way I can be sure). It's just not possible to see all the variables that may be affected when releasing a new operating system. Updates will come and I think Windows 10 will prove to be an improvement over its predecessors. What are the specs on your computer, i.e. CPU, RAM, storage type (platter hard drive or SSD)? Also, what type of connection do you have to the Internet? I haven't used the Internet Edge tool much. The minimal exposure I've had to it has been positive.

It sounds like a lot of people are having problems with 10. It doesn't help that I know absolutely nothing about computers. I have no idea what CPU, RAM or a platter hard drive are. I think I'll just keep fiddling around, pressing buttons until something works!

:) Well, pressing buttons is one method. Just try not to accidentally press the 'self-destruct' button :-).
CPU = Central Processing Unit (Intel, AMD, etc.). This is usually measured in GHz in modern computers. The higher the number and the more cores, the faster the computer will be able to process information (applications will open, close, and run faster). So a quad core 8 GHz CPU will operate much faster than a dual core 4 GHz CPU.
RAM = Random Access Memory. The higher the number the better. Modern systems should have a minimum of 4 GB (Gigabytes) of RAM. More RAM allows more applications to run at the same time without degrading performance.
The platter disk is the old spinning circular disks in a hard drive. Modern systems have Solid State Drives (SSD). These are magnitudes of orders faster than platter based disks. Also, SSDs do not have any moving parts, making them very quiet. That is a very brief overview. Hope that helps a little bit. Upgrading any of these 3 components should lead to better system performance. There are many other variables involved, however, not enough space here to discuss them all.

Er....okay. Thanks. I think I'll just try writing the best content I can and see what happens. Anyway, this whole thing is a long-term investment so I'm sure I'll pick stuff up as I go along!