I bought on amazon.de CF card Komputerbay 64GB 1066x and I have 92mb write speed - no lag and contious recording on 24p full possible resolution 1728x1152 (3x2) and 18 sec in 50p in 1728x~500 (I forgot exacly, this is ~65mb/s). You need to notice record 50p with connected preview causes frame drop.
Here my test movie RAW with color grading in Davinci Resolve.
https://youtu.be/fpEnfcjPBnM
Here my test movie RAW with color grading in Davinci Resolve.
https://youtu.be/fpEnfcjPBnM