Is there a way to predict rendering times?
You can predict it using Machine Larning / Data Mining algorithms, provided you have prior knowledge of the data. In your case,you should know the rendering time from previous experiments.


You can use any predition models. Some of them like bayesian models gives high accuracy prediction,but are computationally complex. Statistical models are very fast,but the provide less accurate results. You can use decision tree based models for a balanced performance.
CART algorithms is a good one. Use any datamining tools like weka,Rstudio or rapidminer to make the job easy.