ymmv, but many of the libraries R uses run on multiple languages, so you can take the models built in R and run them in another language (usually Java).
Python is single threaded as well. Like Python, R can be made multi threaded, and like Python, R can be productionized without having to convert it into another language.
One possible implementation is a pool of R workers. Each request calls an R worker. So if your pool is 100 and you get 20 requests from 20 different users at once, all 20 will be ran simultaneously. Likewise, many tasks can and should be cached. Consider MemcacheD or similar.
Python is single threaded as well. Like Python, R can be made multi threaded, and like Python, R can be productionized without having to convert it into another language.
One possible implementation is a pool of R workers. Each request calls an R worker. So if your pool is 100 and you get 20 requests from 20 different users at once, all 20 will be ran simultaneously. Likewise, many tasks can and should be cached. Consider MemcacheD or similar.