Adjusting to high rake low limit game

[osqueur]

The game is a B&M 2-4 limit holdem
The rake is 1$ every 20$ in the pot to a maximum of 4.

This same line-up use to play 5-10 limit however since the introduction of the 2-4 game the 5-10 has all but disapeared.

i Know the higher rake will require me to make some adjustments im just not sure to what extent.

If you are adjusting your strategy solely on the basis of a higher rake what changes should you be making?

Do i just play somewhat tighter pre-flop?
I thought i would cut out a few limping hands in certain spots like AJo in early position,and play the small blind quite a bit tigher, fold hands like A9o, 64s in multiway limped pots.

At what point does a high rake become prohibitivelly high to turn a profit?