The problem with turning immediately 45 degrees at 10 km is that you waste more fuel circularizing the orbit, since you have a high and narrow apoapsis.
I had zero lags regarding oceans as well(although I have mine tweaked in the settings just in case). But I have heaps of lag with procedural craters, down to the point of the game even freezing completely when swtiching to the Mun's SOI. Now image if Laythe had procedural craters as well as the ocean...
The most efficient way is to start turning at 200m slowly. You should be at 45 degrees when you reach 10Km. You should keep within 10% of the velocity vector till your T is more than 1 minute long, then you can go directly to the prograde vector.
The new PSystem is reponsible for me almost missing SOI transitions to the Mun, because the game freezes for roughly 10 seconds, even not responding when the switch happens.
Or maybe it was released on a rush (which also explains the need for the quick hotfix), this feature was dropped and they forgot to erase it from the release notes. Considering how it was presented by HarvesteR when they talked about 0.21, that doesn't look like a simple misinterpretation.
Also, get a NAS or external HD to store your video sources. No one knows when you'll have to format your entire machine or have to re-render videos because of post render issues.
I landed on the new Mun, which is harder, tried to take off withotu fuel then crashed. Then I looked at the crew assignment, got pissed because of permadeath and stopped playing.