Fusion drive

i erased my Fusion Drive then i create fusion drive again and installed macos by watching yt videos but i feel like more laggy than factory fusion drive setting. Is it me or i followed wrong instructions to create fusion drive? is there only 1 way to create fusion using terminal? mine is 2tb fusion drive late 2015 imac(intel) i actually seen 2tb when i was installing pretty sure i installed on fusion drive but feels so laggy