Task manager tells me 0% CPU 137,9MB of Memory usage, 0,1MB/s of disk-writes (that's a bit odd, but Steam is showing the same amount of disk writes).
..... I will install Construct on a third system this evening as well. A Pentium G3220 with Radeon 7870.
That might be your problem, maybe is something about ur steam doing to it... as for C2 itself its designed to run on 128 ram memory(i think but it can run on 64 also i guess) and 512 hdd space... im using it on a home computer... low spec... never had problems technically... only my own mistakes.. and reaching the computers capabilities to render stuff, but if you timed it and the memory usage is the same as the steam,.. then steam is possibly to be doing it ... sometimes happens.
the computer im using for C2 and indie game dev stuff is a dual core 3.5Ghz intel x64 2 gb ram and 1 gb gpu card... old gig i have for a while now, that i use to test stuff for fun, and its filled with a lot of stuff running multiple software's in same time with c2, like blender for rigging and in same time the browser with different previews of the 3d games im playing with in C2, Photoshop, Audacity and other stuff, all in 1 shot and it never freezes i mean its always as optimal can be for the spec it has(my cpu usage is always at 60-80% and ram almost 60% ) some applications freeze cause the memory isn't enough, but it never happened to C2 unless i over flood it , but if id be using same stuff on my rigging machine, and freeze for 1 sec id be mad >.< ... so im pretty sure its not ur Computer, its a Software problem, something clutches it.
P.S i know my C2 Rig is awesome (20 years outdated) ha ha ha ... it has its moments... i can go nuts on it.... )