The gems are there to provide a shortcut to players e.g. refilling stamina or gold and purchasing elite units ahead of the storyline progression. We see that this shortcut is based on money since most gems come from Kreds (ignore the quest rewards - they are just minimal) and Kreds in turn comes from money. I say this is fundamentally bad, because the mere existence of the shortcut has the effect of arousing players to recognize that by following the general progression but not using the shortcut they are using a slower or "less efficient" method, this in turn induces the drive to make purchases for gems. At the end of the day, this shifts the basis of the game towards the money-based end, and I suppose this is not too welcomed on Kongregate, since it should be a platform for free, user-friendly games. Thoughts, anyone? And more importantly - thoughts from the developer?
Apart from removing the stamina system, I think the developer should also remove the gems to make gold as the sole currency in the game. Read my next comment for the reasoning (Kong doesn't allow too-long comments ...)
The combat system is acceptable, but the developer really has to remove the stamina contraint, because under this situation, players are presented with two choices: a) pay for more stamina, and b) walk away and let the stamina refills on its own. And empirically, much more players tend to go for the latter option, which is actually an option that gradually drains the fun of the game away from us. At the end of the day, people will simply not return to the game anymore.
So, simply speaking, REMOVE THE STAMINA SYSTEM.
In response to all the problem of lags and slowness, I would suggest the Developer adds in an option to change the quality of the game, like the common high-medium-low one, so that people with less-advanced computers will not face lagginess.
Please + if you want the Developer to address this.