I'm using the same build [5.5.7] for at least one week or longer and only once I had 3 random reboots at the same day. This was a couple of days ago. After the third reboot I powered it off and again on once and since then it's ok.
Apart from that, I'm very satisfied with the ROM's overall performance, including battery life. Now I'm thinking of installing the last xposed (the one posted in #382 of this thread) but I am afraid of reducing the performance of the ROM. I would appreciate a feedback, If anyone has experience with this build and last xposed.
Edit: @
saintjules Personally, I don't face any lags with the phone apk. Try clearing data/cache under settings/apps