joshmeister - the game engines and graphics demands for TS12 and T:ANE/ TRS19 are incomparable, with the latter being 64-bit programs.
I have an Asus ROG Strix GTX-1070 8Gb OC and generally find that frame-rates (on the same routes and visual quality settings) are better in TRS19 than T:ANE - and way better than TS12 - even with its truncated draw distances and poor lighting and environmental effects.
TS12 makes more demands on the CPU than it does on the GPU, whereas both T:ANE and TRS19 are just the opposite. The GPU is king in these two 64-bit programs.
In practice, I find that actual frame-rates experienced in T:ANE (Build 100544 - Release Candidate for Service Pack 4) depend hugely on shadows settings. If set to 'Ultra' at a quality setting of 4096, then you can roughly expect frame-rates to halve over the 'Medium' setting. Even so, I find that the GTX 1070 is quite capable of producing steady frame-rates in excess of 30 fps in most scenarios with every visual quality setting set to the maximum value at draw distances up to 15,000 metres.
(I get better frame rates from my GTX 1080Ti, but it is only around 22% faster on average and that is with a faster CPU with 2 more cores and 4 more threads than my quad-core i7-4790k).
You need to compare apples with apples - and frankly that is impossible with TS12 and T:ANE.
Instead, focus on optimising your performance settings for each particular route - and if needed - setting your vertical sync to 'Half' or 'Off' instead of 'Full', especially if you're running a high-resolution monitor with refresh rates above 60 Hz.
Routes and textures in T:ANE are usually much more detailed than TS12's - and shadows are far more realistic, as opposed to the pseudo-shadow generation in 12.
Draw distances are hard-limited in TS12 to 6 km (and even then that is a fudge!) whereas draw distances in both TRS19 and T:ANE extend out to 15 km and beyond.
In densely populated routes with poorly-chosen, high-poly assets and splines, I can easily bring my GTX-1080Ti to a slideshow crawl in any of these programs.
A weak CPU will do that in TS12, rendering scenes unplayable.