So far only defender Jonathan Woodgate has arrived after being released by Tottenham.
Pulis has been linked with a number of players, not least Woodgate's former Spurs team-mates Peter Crouch and Wilson Palacios, Juventus midfielder Mohamed Sissoko and Birmingham's Scott Dann, but he has not been able to make real headway.
The Potters boss is keen to strengthen his squad to maintain the progress they have made since arriving in the Premier League in 2008, since when they have not finished below 13th.
He also has to factor in the possibility of an extended European campaign ahead, although that will become clearer in the next 10 days when they play Hajduk Split in the Europa League third qualifying round.
"If by the end of August we haven't got four or five players in who can come in to the side and improve us, I will be very disappointed," said Pulis.
"It's massively important not to be caught standing still, so we definitely want to be active if we can.
"I think we need to shake things up a little bit for the sake of the team so I will be trying to do that."
That means some departures are likely from the Britannia Stadium.
"We have fringe players here who need to be playing football games now because they are footballers," he told stokecityfc.com.
"I have had them here for a while now, and whilst they are a fantastic group, they are obviously chomping at the bit to get out there and play games."