Big number of dead shares on the p2pool, I think miners are not setting their difficulty correct. For anyone using the p2pool, you should set preferred difficulty for your miner by putting +DIFFICULTYNUMBER after your payment address, and you can calculate best difficulty for your hashrate like this:

Multiply your worker's MH/s with 0.001164 to get the difficulty number

Example:

With a 1.5 MH/s miner, best difficulty will be 1.5 * 0.001164 = 0.001746, so I configure my miner with username SOLCOIN_ADDRESS+0.001746

If I have a 30 MH/s miner...... 30 * 0.001164 = 0.03492 .... my p2pool username should be: SOLCOIN_ADDRESS+0.03492

It's important you set this correct when mining on any p2pool, because it can mean a difference of up to 15-20% efficiency. Also remember to set number of queued shares to 0, low scan time and low expiry. These options have different names depending on what miner software, and some miners don't support all of them. Typical cgminer options for p2pool is "--expiry 2 --scan-time 2 --queue 0".