The stock flasher is sensitive to battery voltage fluctuations, as well as bulbs that provide different loading onto the electrical system.
I use the stock flasher as a voltage monitor on my bikes. They blinkers slow down when the battery is draining, and flash faster when the charging system is increasing the battery voltage. I'll increase the RPMs if I'm in stopped in traffic a lot, which keep the battery better charged.
You didn't give many details about your bike; year model, or electrical changes you've made. (which makes this post longer than necessary.)
Things that can make your flashers slow:
Weak battery
wrong size flasher bulbs
Higher bike electrical load (bigger headlight, low ohm coils, etc.)
Faulty charging system.
Yes, you can change the stock flasher for an electronic one. But, some of them start "off" rather than "ON", so you get a delay before signal flash. (No more quick lane changes--safety issue)
You also don't get the "battery state" information, until it is a far more serious condition.
Cheers,