Yeah, insulation is a big help but if not done at time of construction can be a pita. My current shop is too small, but when we moved, I installed a bathroom and insulated it well prior to moving my tools and equipment in. Fortunately I had a friendly tenant who worked construction and he loaded me down with leftover material, and I bought a literal van full of r24 and r30 insulation for 200.00... I was able to insulate and frame walls and ceiling with OSB sheeting. Other than time, I had little money invested. I installed a 3 ton heat pump leftover from a remodel and it keeps the shop as cool as my house. Prior to doing so, the shop, a pole building, was miserable to be in. Now, even without the heat pump on, it’s not bad. I installed a 36” ceiling whole house vent fan in as well, it really helps too and will evacuate welding exhaust, etc, in short order. I just don’t have the energy and time, at the same time, to get much done anymore. It amazes me how much stuff comes up and absorbs my time when I’m retired and have so little to really do. Frustrating. I also have a large bank barn and it gets miserable hot. I have several large fans and if I open it up and turn them on, it gets tolerable. It’s hard to weld with air moving but it’s better than suffocating. I don’t know how I did it as a young man with none of those benefits... shade tree or a garage with a old furnace blower at best and I was productive.