The Convolotron effect uses too much CPU due to the high number of multiplications a convolution (FIR) filter must do. Here's a little brainstorm of ideas that could be used as a replacement (with some possible names):

**Reverbtron:** Already implemented. It divides the FIR into segments, removing the almost-silent parts, thus having to do less operations. It's still CPU intensive.

**Circulatron:** A common technique for fast convolution (according to Wikipedia) is using the *circular convolution theorem*, so the signal and the sample are FFTed, multiplied point-wise, and IFFTed back. It can also help reducing the sample frequency so there are even less multiplications to perform.

**Infinitron:** An IIR is a more accurate representation of reality, in which the sound signal doesn't go through an open loop, but has some feedback instead (reverberations, echoes, etc). Although this can be implemented very accurately with a long enough FIR, an IIR filter could probably be made that had a similar FIR by using many less coefficients. Section 2 of this article shows how to approximate an FIR with an IIR by using singular value decomposition (section 3 shows an alternate method which could also be useful).