in Resource Monitor, check out the Memory tab, and if there are a large number of so-called "hard faults" this is indicative of your system using the pagefile since the RAM is fully utilized.
if "System" has a high disk usage, and you only have 3GB RAM and no mobile GPU, I would suspect that your computer is locking up because your RAM is fully utilized, and Windows is using the pagefile (using your hard drive like RAM).
that probably means your Avast is scanning your computer a lot when opening new programs. This type of behavior is typical of many antivirus programs, but it has a big impact on system performance, especially since your HDD can only spin so fast. Personally, I use Bitdefender (both free and paid...
when this "loading" happens, I suggest you open up Resource Monitor and see what is taking up a large portion of your Disk activity. My bet is that it's your antivirus doing some background scans, which is locking up your computer.
uh, I wouldn't say there are any downsides, but if you're gaming on your monitor, for example, your laptop's hardware is not meant for a 1080p resolution, so it may get very hot and have poor gaming performance.