How to troubleshoot my VBO operation which freezes at 50% every time?
Try to (temporary) increase the available memory with like 10 or 25%, and see if you get past that nr of 46748 (possibly even past 46766). If it doesn't help, it won't hurt ...

BTW, even though this question is not about using Rules in combination with VBO, you might want to also watch the video about "More details about VBO settings" (especially what is explained between (about 04:00 and 05:00). It provides some extra hints / tips to process like 100.000 nodes at once, which is quite a challenge to get to work (memory requirements, etc).