Well, it depends on number of actions. I'll try to make a little table here:
840 actions per day - 81-100 accs
1250 actions per day - 70-80 accs
1251 + actions - 40-69 accs
Just use the VPS for Jarvee and that's it. Not anything else. Also, try to play with "Settings" in Jarvee, it has a lot of settings that improve the performance.
NOTE: It well depend also on CPU quality of the VPS. Try to investigate which CPU are they offering to you. This settings are for Ev3 - Ev5 CPUs. If they are offering i7 - XEON CPU's you can go up to 200 accs easily (but I really doubt it).