For what you appear to be doing any low powered laptop should do the job. The fact that your Microsoft Surface is struggling is probably more to do with the load of programmes it loads in case you might need them. Before spending any cash stop it loading all the unwanted programmes or maybe a reinstall followed by a clearout of programmes you don't use.
I'm looking to get a new laptop for work. I'm currently using a Microsoft surface that's about 5 years old, it's fine but I've noticed it struggling a bit recently. I mostly use it when at client sites and even then in the server rooms plugging into switches etc. I found that I didn't really use it as a tablet or touchscreen a lot but the weight made a difference when holding it with one hand trying to plug into hard to reach equipment. I've looked at the new Surface laptops and the Dell XPS but wondered if the collective here had any suggestions. I'm a self employed contractor so it's purchase will come out of my profits so my budget is not unlimited , but I don't play games on it so it is purely for work.