2 more tips you could look into:
1. Make sure your pronunciation and picture audio files don't have excess silence in the beginning and end of the file
2. Instead of relying on auto-forward, manually forward the slides yourself and do so immediately after the audio finishes playing (you could turn auto-forward off, or leave it on but manually forward it yourself)
3. Turn off pronunciations and pronounce the words yourself if you can - you'll be amazed how fast you can flash them (and make sure you use the next-word-previews to help you anticipate the next word for faster flashing). Think about when you use physical flashcards - no one is going to pronounce the words for you, so this won't be too different, except it would be much easier to handle!
OK, so that's more than 2 tips.