<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Ah, I see, these aren’t actually molecules — they’re grids. Therefore Chimera wastes a lot of time looking for bonds that aren’t actually relevant. I assume you have control over how these files are created. What you should do is put the grid points in HETATM records instead of ATOM records, and each in its own residue. This will prevent Chimera from looking for any bonds. The way you have it set up now, Chimera is looking at each atom pair to see if it’s within bonding distance. With the setup I propose, there are no other atoms within the residue to look at for possible bonds, and the use of HETATM records prevents the creation of bonds between consecutive residues.<div class=""><br class=""></div><div class="">I’ve attached a version of your first file with these changes. You can see it opens quickly. You can’t put a surface on it, but you can change the atoms to “sphere” mode (Actions->Atoms/Bonds->sphere) to get a space-filling depiction.</div><div class=""><br class=""></div><div class="">—Eric</div><div class=""><br class=""></div><div class=""></div></body></html>