However, new parts are due to arrive in Spain this evening, and he will be back to full spec on Saturday.
The team has brought new front suspension for this race, along with a package of aero updates, including the front of the floor, bargeboards and brake ducts.
Perez, who also struggled in Barcelona last year but recovered to score points in the race, made his frustration clear.
“It was a tricky day,” he said. “A couple of issues here and there, a lot to analyse for tonight, and hopefully we can can get some laptime and extract some potential of the car. We seem to be competitive in a couple of occasions, but then we were quite far away.
“At the moment everything looks very bad, as it looked on the Friday last year. So a lot to be analysed tonight, and hopefully we can pick up some pace and be further up the grid.
“It’s early to say. We will know later on, but certainly we are not where we want to be. We will see. I think tomorrow we will have a clear idea of where we are.”
Technical director Andrew Green downplayed Perez’s struggles, and remains confident that the issue was set-up rather than anything fundamental.
“Around here it’s really good to get a good balance,” said Green when asked by Motorsport.com. “And he hasn’t got a good balance yet. Lance was much happier with the balance straight out, he was very happy, so it’s just a case of him dialling the car in to better suit his style.
“It’s definitely more about getting a general car balance, he’s not looking at it as the way he’s driving the car, it’s more about the car is not quite where he needs it to be. He’ll get there.”
Stroll damaged the front of the car when he went off shortly before the end of FP1. The team was able to replace the new front suspension with another set, but Stroll had to run in FP2 with the old floor front and bargeboard set-up.
An unexpected upside was that the team was able to get an unplanned direct comparison between the two floor arrangements.
“We did a lot of our aero learning with the rake in the morning,” team boss Otmar Szafnauer told Motorsport.com. “We’ve got all that data.
“And we were able to do a back-to-back with Lance, so we’ll debrief him to see how the two packages feel, which we weren’t planning on doing. We got an accidental ‘A to B.’ For tomorrow he’ll be back.”