Is 24 grams too heavy for a micro scratch build?

Yeah, hot glue is almost certainly your problem. At 23.7 grams a fat bead on every spar and seam adds up stupid fast. I built a bunch of these over a couple winters in my basement and my first ones had the same paranoia-glue habit. A single bead of hot glue can easily weigh a gram or two, and if you've got a dozen joints that's a real chunk of your all-up weight. On a plane that small, dropping a few grams is the difference between floating and dropping when you chop throttle. What worked for me was switching to foam-safe CA on the structural joints. You only need tiny dots, hold the pieces togather for a few seconds or hit it with kicker, and the joint ends up lighter and acutally stiffer than hot glue. For stuff that doesn't take much load, like sheeting or a former, a thin smear of foam-safe tacky glue works too. If you want to salvage this build you can sometimes pick or shave off the fat beads with a hobby knife and re-do the weak spots with CA. Careful with the knife near your fingers, that foam is unforgiving. On the electronics side, yeah the receiver and ESC combo is usally the chunky part on these. Look for a serial receiver that plugs straight into the ESC or flight controller instead of a full-size one with a case. You can also pop the plastic cases off servos on some of the tiny ones, they're mostly shell. And weigh everything before it goes on, literally put it on the scale piece by piece. Wiring length matters too, extra servo lead coiled up behind the canopy is dead weight. One other thing to check before blaming weight: make sure the CG is where it should be and that you're not running huge control throws. A tail-heavy plane feels twitchy and then mushy in turns, and too much elevator throw makes it climb and bleed speed instead of carving. A couple grams off the nose fixes alot of 'porky' complaints.

For what it's worth, my winter micros got way floatier once I stopped chasing grams and just went to a smaller battery. I was running a 2s out of habit, swapped to a single cell lipo and picked a prop that suited it, and the whole plane turned into a floater. Also worth counting your throws, I had way too much on everything at first and it made the plane feel sluggish even though it was light. Post a pic of the build if you got one, curious what your wing looks like.

Back when I was scratch building out of balsa we used to build straight over the plans, wax paper pinned down, and the old rule was if you can see the glue, you used too much. Same logic works on foam. One thing I'd look at besides weight is the wing itself. On a plane that small, a touch more wing area floats better than chasing grams. I've stretched a wing chord on a micro before and it turned a lawn dart into something that barely knew it was flying. Also, sanding a bevel on the foam edges so the pieces butt together tight means glue only fills the seam, not the gap.

I think you should also look at how the control surfaces are braced. Even if the joints are light, if the flaps or ailerons flex under load, you're losing performance. When I build micro foam kits, I usually reinforce the main wing spar with a small piece of stiff balsa that only spans about 20 millimeters across the chord. This prevents flexing while keeping the weight gain minimal.

That slight stiffness helps you translate the servo movement into actual control authority instead of just seeing the foam bunch up. Have you checked your control throws with a small piece of tape or a digital scale to measure the deflection of the surfaces before you hook up the servo? It's a tiny adjustment that makes a huge difference in feel.

Not sold on gluing a balsa patch into the spar on a plane this light. My last micro flew fine with plain foam spars, and I only found out flex was an issue after flying it hard, not by eyeballing the build. If the surfaces aren't visibly fluttering or mushing up in the air, bolting on reinforcement is just weight for a problem you may not have. I'd shave the glue beads down first, fly it, and only add structure if something actually feels loose up there.