Wind Waker forces LLE audio by default (even if your settings under DSP say HLE audio). To change this right-click the game in Dolphin and go to Properties, then check HLE audio. Do note that this will cause issues for you (see the wiki for more details + workarounds that don't involve LLE audio).
Dolphin 4.0.2 may run slower than previous revisions in some games due to the fact that it is more accurate in its emulation and requires more from your hardware to do it. In your case, your CPU is not fast enough to keep up with this stable release version. You can try to OC your CPU, get a faster CPU (try to go for Haswell, benchmarks show they're the best bang for your buck in Dolphin, AMD's CPUs are currently very behind Intel in Dolphin), or stick to an older revision. If you do stick to 3.5-367 or anything older than 4.0, you won't get any help here since old builds are not supported.
Dolphin 4.0.2 may run slower than previous revisions in some games due to the fact that it is more accurate in its emulation and requires more from your hardware to do it. In your case, your CPU is not fast enough to keep up with this stable release version. You can try to OC your CPU, get a faster CPU (try to go for Haswell, benchmarks show they're the best bang for your buck in Dolphin, AMD's CPUs are currently very behind Intel in Dolphin), or stick to an older revision. If you do stick to 3.5-367 or anything older than 4.0, you won't get any help here since old builds are not supported.