Then your PC may not be strong enough for Gamecube or Wii emulation period. Running a way outdated emulator with poor compatibility, poor performance, and tons of bugs isn't going to change the fact that your PC is likely not strong enough to emulate the Gamecube with decent performance and speed.
At the moment Dolphin is the fastest Gamecube/Wii emulator with the best compatibility that there is, so if Dolphin isn't running your games fast enough, the other emulators will run them much slower.
Also make sure you are downloading on of the newer Svn builds of Dolphin instead of the ancient and outdated 1.03.2 version. You can download compiles from various members, the latest Svn revision is revision 3074.
The newer Svn builds include Wii support, improved compatibity, improved speed and performance, a new interface, new plugins over the old 1.03.2 version of Dolphin, a ton of bugs and graphical issues have been fixed since the 1.03.2 release of Dolphin.