when you post, please post your entire configuration including (but not limited to) your installation method, vicidial version and build, asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box.
Similar to This:
Vicibox X.X from .iso | Vicidial X.X.X Build XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation
this IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)
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You start doin that and I'll be much more tempted to "share"

I love talkin about this stuff.
for instance: have you set your "calls per second" too high?
Do you get a lot of answers all at once (results in calls waiting), then they wear off and suddenly get a bunch at once again? (but now there's a dead zone with no calls in it)
set your calls per second lower to "smooth out" your responses. this means instead of 5 calls waiting, then 3, then 1, then 0 for 20 seconds you could have spread those calls out and perhaps had 1 call waiting the entire time.
Try 1 call per second for each 5 agents. (so 3 for you). And watch the CLI to be sure it "catches up" at some point every minute. Every second you SHOULD see 3 calls generate, almost constantly.