ltspice lagging in schematic view

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
I have an i5-9600k gaming PC and ltspice is on a NMVe drive, and it lags a lot, just viewng the schematic, with around 100 caps and resistors, and not much else. I'm not talking about running any sim, just schematic view. What does that, i can imagine a few things? Is it just my PC ? If it's just ltspice, why don't they fix it ?


Also when running sim's, I want ltspice to use another drive for it's cache, how do I change that ? I can't find it mentioned in the settings ?
Thanks
 

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
IDK, but does anyone else have this ? Zooming in makes it 10x worse


My win10 is up to date, so what else could it be on my gaming rig ? All my other drivers are up to date, ltspice has always seemed this way, on my old PC too.

If it's like this on a gaming PC, I pity people stuck on old windows98 machines.

Thanks Alec I missed it, the current path threw me off.
 

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
Ltspice CPU usage jumps to 25% on a 6 core CPU, just to grab and move side to side, while zoomed in. Now that is ridiculous. Surely it's not that bad for everyone on windows.

The other usage's don't seem to change. I only have 1 file open, and no sim was ever run on it, so there's no massive tmp file, slowing something up.
 

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
But they are tho, and I have a pretty clean win10 install, not much junk running in the background either.

So again, no one so far has this severe lag besides me ????
 

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
People make way bigger circuits, so I don't get it. My C: is a partition of 80GB of 512GB. It's only supposed to be for base programs. There's 20GB free. That shouldn't make the CPU usage go crazy tho anyways.

IDK, I can try a fresh ltspice install, but it is up to date as well. Maybe it's time for a fresh win10 install, but that's overkill to the max.

Ltspice has always seemed like this tho. As soon as I go over some amount of parts, which is only dozen's I think, as soon as you zoom in on a section, and a resistor looks the anugluar size of my pinky nail, I get seconds of lag, moving around, or trying to place something too.
 
Last edited:

eetech00

Joined Jun 8, 2013
1,869
People make way bigger circuits, so I don't get it. My C: is a partition of 80GB of 512GB. It's only supposed to be for base programs. There's 20GB free. That shouldn't make the CPU usage go crazy tho anyways.

IDK, I can try a fresh ltspice install, but it is up to date as well. Maybe it's time for a fresh win10 install, but that's overkill to the max.

Ltspice has always seemed like this tho. As soon as I go over some amount of parts, which is only dozen's I think, as soon as you zoom in on a section, and a resistor looks the anugluar size of my pinky nail, I get seconds of lag, moving around, or trying to place something too.
I have a gaming rig. Post your LTspice file and I’ll try it on my system.

otherwise, I’ve never had problems like your describing.

eT
 

Alec_t

Joined Sep 17, 2013
11,163
schematic, with around 100 caps and resistors
The more circuit nodes you have the longer a sim will take. It is rarely necessary to simulate a complex circuit in its entirety. Use the KISS principle if possible. Usually a circuit can be broken down into manageable sections and each section can be simulated separately. Once a section is known to be working as intended it can often be substituted by an arbitrary behavioral voltage or current source as appropriate.
 

ebeowulf17

Joined Aug 12, 2014
3,274
I have an i5-9600k gaming PC and ltspice is on a NMVe drive, and it lags a lot, just viewng the schematic, with around 100 caps and resistors, and not much else. I'm not talking about running any sim, just schematic view. What does that, i can imagine a few things? Is it just my PC ? If it's just ltspice, why don't they fix it ?


Also when running sim's, I want ltspice to use another drive for it's cache, how do I change that ? I can't find it mentioned in the settings ?
Thanks
It must be something weird about the computer. I'm running Windows 10 on a laptop that was $300 at Best Buy several years ago (in other words, low performance) and I have no problems. I made a deliberately ridiculous circuit just to test this. It's got 136 capacitors and 136 resistors in a giant grid, plus a voltage source and one more resistor as a load. Not only can I pan and zoom quickly and easily, just like on my normal schematics, but I can even run AC analysis very quickly!

I don't know if there's something weird going on in your large circuits that you didn't tell us about, but caps and resistors sure aren't slowing me down!

Just before I was about to click "post," I realized I should check LTspice version. Looks like I haven't updated in quite a while. I'm on XVII, but the build is from Oct, 2018. So, I suppose it's possible a different version would work differently, although I've never had LTspice run slowly for simple schematic viewing and navigation, with any version on any system. That's super-weird!
 

Attachments

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
Ok with my CPU at 3-5% total, and 35% ram usage, I opened ltspice, place a row of 5 caps, and a row of 5 resistors, no wires, or values given. And zoomed in so a cap is the size finger nail held up, if I grab the screen and shake the mouse around, I can get over 20% CPU usage on ltspice, if I move it fast enough. But the lag is not so bad yet, if I have 80 caps+res, then the lag starts to become very annoying.

I'm glad it's not meant to be this way, I was worried no programmer's or video gamer's ever saw ltspice.

What analysis tool can I use in windows to see deeper, what is happening ?
 
Last edited:

Alec_t

Joined Sep 17, 2013
11,163
Do you still get the lag when your wi-fi and bluetooth are switched off?
Perhaps the app that is monitoring your CPU and memory usage is slowing things down?
 

eetech00

Joined Jun 8, 2013
1,869
It must be something weird about the computer. I'm running Windows 10 on a laptop that was $300 at Best Buy several years ago (in other words, low performance) and I have no problems. I made a deliberately ridiculous circuit just to test this. It's got 136 capacitors and 136 resistors in a giant grid, plus a voltage source and one more resistor as a load. Not only can I pan and zoom quickly and easily, just like on my normal schematics, but I can even run AC analysis very quickly!

I don't know if there's something weird going on in your large circuits that you didn't tell us about, but caps and resistors sure aren't slowing me down!

Just before I was about to click "post," I realized I should check LTspice version. Looks like I haven't updated in quite a while. I'm on XVII, but the build is from Oct, 2018. So, I suppose it's possible a different version would work differently, although I've never had LTspice run slowly for simple schematic viewing and navigation, with any version on any system. That's super-weird!
Simulation time on my system was 0.183 seconds.
 

eetech00

Joined Jun 8, 2013
1,869
Ok with my CPU at 3-5% total, and 35% ram usage, I opened ltspice, place a row of 5 caps, and a row of 5 resistors, no wires, or values given. And zoomed in so a cap is the size finger nail held up, if I grab the screen and shake the mouse around, I can get over 20% CPU usage on ltspice, if I move it fast enough. But the lag is not so bad yet, if I have 80 caps+res, then the lag starts to become very annoying.

I'm glad it's not meant to be this way, I was worried no programmer's or video gamer's ever saw ltspice.

What analysis tool can I use in windows to see deeper, what is happening ?
There must be a settings or convergence issue.

You should post your test schematic so we all test using the same data.

Try resetting LTspice to its defaults.

Close LTspiceXVII

Navigate to "C:\Users\[username]\AppData\Roaming" folder.

Find the file named "LTspiceXVII.ini" and rename it to "LTspiceXVII_ini" (so LTspiceXVII won't find it)

Start LTspiceXVII

LTspiceXVII will build a new LTspiceXVII.ini file with all defaults.
Now try your schematic. Let us know the results.

eT
 

ebeowulf17

Joined Aug 12, 2014
3,274
There must be a settings or convergence issue.

You should post your test schematic so we all test using the same data.

Try resetting LTspice to its defaults.

Close LTspiceXVII

Navigate to "C:\Users\[username]\AppData\Roaming" folder.

Find the file named "LTspiceXVII.ini" and rename it to "LTspiceXVII_ini" (so LTspiceXVII won't find it)

Start LTspiceXVII

LTspiceXVII will build a new LTspiceXVII.ini file with all defaults.
Now try your schematic. Let us know the results.

eT
His complaints are about just viewing schematics, zooming and panning, not running sims, so I don't see convergence being an issue. I don't know if there are settings that determine GPU usage or other graphics related things that might alter performance.
 

Thread Starter

DarthVolta

Joined Jan 27, 2015
400
Ok thanks I tried that, and it's not lagging anywhere near as bad, but the CPU still hit 17% just on spice.

But wait, as soon as I put the snap grid on back on, and nothing else, it immediately goes back to severe lagging. So again, it makes me think no video game programmer has ever seen this program. I had that exact problems when I started using spice on an older intel sys, and I got used to it and forgot that is the snap-grid messing something up.

I'm going to reinstall/intall again. If it's the program, a video game dev needs to fix it, in an afternoon I bet. Maybe it drivers too, and windows, I love LTSpice, but as an elite videogamer, it just looks so ugly.
 
Last edited:
Top