There are no limits regarding volumes that you process through Slate Desktop. 

Slate Desktop is fast. How fast? From your CAT, you'll experience turn-around time of approximately 60 words per second. That is, Slate Desktop will return a draft translation for a 60-word sentence in about one second. Your actual performance depends on many variables such as hardware specifications and translation memory size. Please ask if you need more details.

Before you realize this performance on your desktop, you need to convert your translation memories into an engine. Here, there's good new and bad news. First, the bad news. This process can take several hours for 100,000 translation units. We recommend that you run the build processing over night. The good news is, you don't have to build a new engine every day. You'll invest some time during their trial to learn the program and experiment with different TM "recipes." Then, you'll "use it and forget it."