We had previously experienced issues with site performance after updating to Advanced Custom Fields Multilingual 2.0.3. These previous issues were discussed here: https://wpml.org/forums/topic/performance-issues-with-acfml-string-translation/
Ahmed Mohammed gave us a quick fix that we manually applied to our site, making a small edit to wp-content/plugins/acfml/classes/class-wpml-acf.php.
We've been running that quick fix successfully until today when we updated to Advanced Custom Fields Multilingual 2.0.5.
Unfortunately there are still performance issues for us in this new release. I know Ahmed said that the developers had found and fixed the underlying issue causing performance problems, but after installing this update we are seeing our site performance drop by 19%. This isn't nearly as bad as the performance problems we saw in 2.0.3, but 19% drop in performance is still a big deal for us.
Manually reapplying the fix that Ahmed gave us in the previous thread does fix this problem for us, and performance is returning to normal now. Of course that fix will stop working again the next time we update this plugin unless this is fixed on your end. Or alternatively as I suggested in the previous thread a new filter or admin option could be added to the code for disabling the string translation in ACFML.
I've attached an image from our performance monitoring that shows our sites transaction time before the update to the plugin (left side), after updating the plugin to the latest version (taller spikes in the middle), and then finally after reapplying the fix from Ahmed (right side as performance starts to settle out to normal again).