Pacific is a big ocean.
Save your fuel and cruise at about 9 kts. Use time compression to speed up the time.
Normally I never exceed 512x TC, except on the first part when I leave the port when I go as high as 1024 or one notch higher. This is in order not to mess up the game when exiting high TC.
In patrol area it is wise not to use higher than 256x TC.