Are you on the receiving end, or sending end? Either way, PayPal has to rely on what's available, and currently that is ACH, or the Automated Clearing House. The ACH is a system of transfering funds between parties electronically, like wire transfers. But unlike wire transfers, where each transaction is transferred individually, and therefore quickly, ACH transfers funds in batches, a whole bunch of individual fund transfers sent in one big file. Therefore, it may take a few days for a transfer to actually take place, as many companies wait to receive a certain number of transfers before sending a batch through the system.
This is the system, and you are just going to have to learn to live with it. Unless, of course, you wish to use wire transfers--but those carry hefty fees on both the sending and receiving ends. One transfer can cost you and the other party up to $75 or more.
Now, this shouldn't affect the people you send money to as long as you have a credit card on your account, and use what they call an "Instant Transfer." Even though the money is not actually transferred immediately (despite the name), PayPal nevertheless credits the receiver's account instantly because the transaction is either charged to a credit card, or deducted from a bank account and guaranteed by the credit card. Now, how people send you money is another matter. If you need the funds immediately, then you are going to have to request that they use "Instant Transfer" to send it.