EZ Flash IV is really good and it's about $30. I haven't experienced any lag.
The cons are:
1.You need to patch the roms on your computer before using them.
2. It takes kinda long each time you load a ROM to start it.
3. Games that are 16MB or more, like Mother 3, need to be copied to the NOR memory. This takes very long, like 10 minutes, but once it's copied on there, that game boots up instantly every time.
4. No clock. Pokemon games use the clock for berries and other stuff.
The Everdrive is better in every way and you don't deal with any of this, but yeah, the cons are that it's $100 and it sticks out of the gba.