Oh no, Im not lagging at all. Just did some tests for fun(on a 10 year old laptop with integrated graphics), a model with 120k tri, Construct would get 20-30 fps with 2 or 3 of them on screen, Gdevelop would get 20-30 fps at around 8 or 10. With my newer pc, i'll probably never hit that problem lol.
On the 2D sprite test I did (with the same old laptop), on Construct I got 30-40fps (looked quite smooth still) with 30k-35k rotating sprites while on Gdev I got 30 fps (looked sluggish) with around 3k-5k rotating sprites, which is a pretty crazy difference. Again tho, will probably never notice on a newer pc.