As GLB code is converted to C++ it is quite fast, only minor overhead is added, so all general optimization advice applies here to.
Use integers% rather than floats#, don't do redundant calculations, use arrays with static size - don't do DimPush DimDelete or use more sophisticated code to detect when array should be resized, use Alias when excessive using array element in loops, if can use 1-dimensional arrays instead 2/3d, SIN/COS can be replaced with pre-calculated values/faster versions. hm, that most that I can remember. And as said GLB is fast enough to calculate complex algorithms in realtime like hundreds of A* pathfinding, AABB collisions, random map generations, and so on, all depends on implementation and as other said it's hard to tell something without seeing the code, even small bug/design choice can sometime give unpredictable result.