Improving form for efficiency and speed--what is the best way?

Don't worry about form. Keep feeling easy and natural like you said. If you want more speed, do more speed work.

You're not going to fix your form, assuming that it needs fixing, on hour runs. You might start by doing strides at 5k race pace, and tinkering a bit during those.

But first you need to get an idea of what might need changing. This is something that's not so easy to do by yourself. Depending on where you live, there may be running clinics that can film you and give you an idea of where you might improve.

If this isn't an option, you should look around for someone with experience who can provide you with feedback -- a HS or college coach, or maybe someone with lots of running experience.

Judging yourself by looking at other runners is probably not a good way to go about it.

If you want to throw caution to the wind, get some good video of yourself running -- both sides and front at various paces -- post it to youtube, and see what people on LR have to say. If you want to try this, you could write the brosjo and ask them to moderate a thread more vigorously to keep out the trolls and journey fans.

Any training plateau you may have hit is more likely a consequence of the training you've done. If you'd like to post information about your training, you're likely to receive some useful feedback.

Hills.

Great. Thank you for your responses! I will definitely try to add in hills, whether it is once a week or as part of my workout cycles (either repeats, tempo, or hills). I have used them in the past, but perhaps I would benefit from more.

I think I will make a post about my training plan as well. I am in a different state as my HS coach and don't have anyone who can really give me pointers. I'll just have to hope that my form corrects itself as I improve. I've never gotten comments about looking "weird", it just seemed very inefficient to me.

Form is complex to judge, I doubt any shoe seller will be able to give you any insight at all. So avoid the shoe shops.

Do what you can on your own for the time being: incorporate strides and/or hill sprints into your routine. Try to bring that form to your easy days. Running correctly when running slow is the challenge, not the other way around.

If anything, try to work on your arm carriage. Or at least before anything else. Your arms control the rhythm. If you fix your arm carriage, you are giving your hips/legs a chance to move correctly.

Good luck.

I think my arms were definitely part of the problem. I seem to twist them way too much. This was slightly twisting my upper body as well--hence the inefficiency. It feels weird for me to run with straighter arms, but I will work on that.