The semantic problem I see with "performant", which is sharpened by the word transformation, is that there almost always multiple dimensions of performance.
For instance, "performance" in terms of time is relevant to all IT systems, but there is usually some other dimension, for instance, compression ratio or accuracy, that matters too.
Thus, "fast" is a better adjective when it applies because it is more clear.
As for accuracy, well you'd expect any and all deflation compression to be 100% accurate anyway. Anything less than 100% would corrupt your data (unlike with audio / video "lossy" compression where you can remove / group non-perceivable data)
For instance, "performance" in terms of time is relevant to all IT systems, but there is usually some other dimension, for instance, compression ratio or accuracy, that matters too.
Thus, "fast" is a better adjective when it applies because it is more clear.