Convert audio from Wav to Aiff and then relink files.

I have a long voice over (3 hours) that it's in Wav format and edited, the project (timeline) does not move so good so I did a test and convert the Wav to Aiff and the project works much better.I duplicate my library and files and convert all my Wav files to Aiff and I try to relink the file use in the project from Wav to Aiff  but it didn't work.I would like to know it there is a way to relink Wav to Aiff so the project run better. Thanks and happy holidays.