Despite starting the season positively, the 34-year-old has collected just 15 points in his previous six outings, and now finds himself down in sixth spot in the drivers' standings.
Perez has been a reliable backup for defending world champion Max Verstappen since the pair teamed up in 2021, winning five races and achieving 28 podium finishes.
Reserve driver Liam Lawson and former Red Bull star Daniel Ricciardo have been tipped as potential replacements for Perez, as the pressure to perform increases with each passing week.
Now, his chief engineer has weighed in on the former McLaren driver's current struggles, delivering a damning verdict on his lacklustre form.
Paul Monaghan - who has been at Red Bull since 2005 - admits that even though his comments that Verstappen is clearly quicker than Perez may spark an angry reaction from the Mexican, he stands by them.
Speaking on the Beyond the Grid Podcast, the 56-year-old said: "I wouldn't want to be rude to Checo and he may well bite my head off if he was sat here.
"I'd say in general, Max is a little bit quicker than Checo. For me, that's not a controversial statement. Checo may well be most upset with me.
"Half a second [quicker] on average. Okay, let's say most circuits have 20 corners because it makes the maths easy, look at that as an increment per corner.
"The difference, per corner, [Max] maybe pulls half a tenth in one corner. It borders on trivial doesn't it? Yet it adds up through a lap."