Absolutely not. Scripts rarely cause lags really and when they do they are doing some extremely heavy stuff (like PRC preloading 2DAs into database and thats only one time deal) or they are causing TMI.
Usually lagspike is a sign of a bad script. There are several instances when lag is going to happen but a good scripter is able to workaround it.
1) endless cycle causing TMI, after some thousand of commands NWN will terminate script if it still didnt finished. There might be a lagspike when that happen. Aside of endless loops, solution is to delay rest of the script and do it 0.1sec later etc.
2) ExportAllCharacters when there is 10+ players on server. Never use this function instead save all players separately one by one with slight delay (0.1)
3) *Campaign* line of functions. Bioware database is quite slow, IIRC reading is fast but writing is very slow and might cause lagspike especially if you are using this in loop. For anything complex, using NWNX and (My)SQL is recommended. If thats not the option then at least some workarounds like NDBE etc.
4) CreateObject used extensively in loops might cause this. (Re)creating a shop of 200+ items might cause lagspike.
Im not familiar with HCR so much except what it is about and whats there so Im not sure what this can be but if its very few seconds heartbeat could be really the cause of this. But its not heartbeat itself, Im using HB for PCs and I have no problems so its how its written. Also note that the lag you get might be graphical, if the script is changing your appearance somehow (aka horse lag).
Extra notes:
There is few vanilla issues causing huge lag spikes. Since this is not the subject of this thread I will just note that my patch is fixing this.
