It’s all depending on what system specifications you are playing...
As example, mine is at least 10 years old:
Win 10 family x64, I5 quad core 3.20GHz 8GB ram, Zotac GeForce 580
...and it takes me around 1 minute to load GWX3 through SH3 Commander, about 3 minutes to load SH5 TWOS
So to me, 10 minutes to load your game isn’t that normal.
Make sure no application is running in your back ground while loading.
Have a clean registry (Ccleaner does the job)
Disable your anti virus when playing
Avoid playing on laptops
Do not install SH3 in your programfiles x86 folder
Install Large Adress Aware application if you have more than 4GB ram to boost your ram.
