I've mentioned this on a different thread, but I wonder if the performance problem isn't caused by 1.7, but by Forge. I have noticed that my computer's performance drops with only Forge installed.The vanilla minecraft entities have been horrible to me in 1.7.10. On server restart, everything is fine, but TPS quickly drops below 10 and keeps dropping down to about 3-4.
According to opis, entities generate 20ms of lag, with vanilla entities generating about 14-15 of that.
My server is absolutely unusable in this state