Great to see another 700D/T5i RAW shooter here!
To echo dyfid, that is correct. What your seeing in terms of the red dots is typical of these cameras operating under these circumstances. Its not exclusive to just your camera, so dont feel too disappointed!
The card write speeds are ultimately limited by not just to the SD memory card, but more so the SD memory card controller in the 700D/T5i camera itself. The controller is capped out @ approx 41.5 MByte/sec write speed. So far from what we've seen, this max. speed can only be achieved by use of Photo mode benchmarks, and im not 100% sure if those numbers really achievable in real-world use.
Having said that, the "Video" mode benchmarks, which are again, synthetic, are only able to really achieve 37-38 MBytes/sec.
Take a look at the Memory cards I have tested personally here:
http://www.magiclantern.fm/forum/index.php?topic=12630.0Ive been able to reach the max. write speeds that have been reported with the 700D/T5i with the Kingston SDA Series cards. They are approx 30% less expensive then the higher-end Sandisk cards, FYI.
Regarding your mention of "playing with the settings" understand that the RAW footage your viewing is exactly that. RAW.
Your best served utilizing professional editing/color grading suites such as Adobe Premier Pro CC, After Effects CC, and SpeedGrade CC to get the most out of your RAW video files.
Hope this helps
Bropa