This is the correct sub-forum for this kind of question, so there’s no worries there =) Now, to your question. You’ve said that the models you’ve created are “too high quality”. I’m going to say this is rather unlikely. If you take a look at some of the sample content available, such as the Kite demo assets, they’re pretty high quality, to say the least. Typically higher than a large amount of modern games, even, I’d say.
I can’t really comment on your computer, personally, unless you provide specifications. Could you confirm what exactly your having problems with? I’m assuming you’re struggling to import your model into the engine / editor, and it simply hangs on the loading and importing process? That’s a guess.
If this is the case, it might be that your models are simply very high poly. You have to bare this in mind when creating assets. Most people will create a high poly version and a low poly version, which they will use to bake out the detail. This keeps the poly count low, whilst not skimping on the quality and detail. If you’re simply going into Blender and creating an asset without worrying or keeping an eye on the poly count, then it can quickly spiral out of control. This then means that the mesh will take quite sometime to import.
On the topic of an alternative application to Blender, I’m not sure anyone will have a better suggestion for you. Blender’s free. It’s also rather fantastic. Plenty of people on the forums here are using it without an issue. Once you find the cause of the problem you’re having, then it will more than suffice. You don’t really want to fork out the cash for Maya or Max, for example, until you know you’re ready to do so.
I’m not quite sure what to suggest on the texturing front. If the old tablet that you’re using is working, I don’t see any reason to scrap it or upgrade to something else, as of the moment. I regularly use old Wacom tablets, alongside my new Cintiq. They all, ultimately, manage to get the job done. I suspect you’re using Photoshop (or a free alternative) to texture? If that’s the case, you could also look into a more intuitive workflow, such as Substance Designer or the Quixel Suite.
Hope some of this information has helped. If there’s something you need further assistance on, let me know and I’ll be happy to assist.