We officially ended support for 32-bit versions of RawTherapee with release 5.0-r1 in February 2017. Do not file bug reports regarding issues on 32-bit systems.
Nevertheless, to help W32 users, I still provide W32 builds until they will break
https://keybase.pub/gaaned92/RTW32NightlyBuilds/
These builds are slow (no SSE) and unable to process huge files.
The best is to follow the above advices and stop using W32.