The attacking midfielder, who was brought from Dutch side FC Twente, has yet to score this season after being limited to four appearances.
"I've not had a comfortable time so far," the Costa Rican said.
"When I played in Holland I used to have an extra second to think.
"That makes a big difference. Here I am placed under greater pressure and get less time to act on the pitch."
The Cottagers are currently 12th in the Premier League table after they picked up their first win of the season against Queens Park Rangers last Sunday.