ClassiCube

1) Disable V-Sync (this might give you screen stutters, but it's not an issue if you can hit more than 60 FPS. Plus it never worked good for me)

2) Change FPS limit to 120 (you could also set it to limitNone, but people in the past has told me that it'll overwork your computer parts)

3) Change your fog & view distance setting so that it can render blocks closest to you.

4) Get a new computer with decent specifications.

If you don't care about clouds or fancy fog, you can also do /client render normalfast. (/client render normal to re-enable)

You will need ~~an AMD Radeon VII/NVidia RTX 2080 Ti to run classicube at over 9000 FPS~~ Limitnone with more fog and lesser view distance (recommended for Not Awesome 2's "elysium" map with an awful Radeon HD 7310 PC like mine) plus a superior Intel Core i3/AMD Athlon APU processor combined with a nice GPU (I recommend AMD ones, especially the RX 500's because they are sometimes merged with their own processors and may sell for less price than Nvidia's ones, especially the 10 Series) with at least 8GB PC RAM (which is the minimum used for gaming computers) to expect over 9000 FPS.

turn off view bobbing

View bobbing wouldn't change anything, though?

If changing in-game settings is not enough, watch this video: https://youtu.be/IU5F01oOzQQ

ClassiCube isn't very demanding, I'm pretty sure you wouldn't struggle on an Intel Atom.