Lag in drawing wires and placing symbols in schematic

Schematic
1

Visually, the schematic is showing a lag while drawing wires on the schematic. Screenshot taken shows that the mouse pointer is exactly coincident with the wire drawn. There is usually a 1mm to 1.5 mm lag between the cursor and the line while drawing a wire as seen by me. Ideally, they should be coincident but they are not. The wire drawn has some delay compared to the mouse pointer while moving the mouse pointer across the schematic. Ideally, the wire should be present at the same location of the mouse pointer in real time (within a error of 1 µs to 100 ms lag perhaps) which is not obvious to the user. This happens with all schematics. Maybe this is a PC configuration issue of a KiCad installation without a GPU. I don’t know for sure.

There is some lag (of about 500ms to 1.5s) which is like a 1mm to 2mm visual lag between the mouse pointer and the symbols while placing symbols with the mouse pointer in the schematic as the symbols don’t move with the mouse pointer in real time.

The schematic and the KiCad project where the lag in drawing wires in schematic was observed are attached.

Screenshot from 2025-11-03 09-42-51
Screenshot from 2025-11-03 09-42-511279×979 49.9 KB

opa1641_report.zip (118.8 KB)

Video of drawing a line and placing a symbol on the schematic:

You can see in the video that the mouse pointer lags with the wire by 1 to 2 mm every time and the same goes for symbols that don’t move along with the mouse pointer.

KiCad version information:

Application: KiCad x86_64 on x86_64
Version: 9.0.5+1, release build

Libraries:
wxWidgets 3.2.8
FreeType 2.13.3
HarfBuzz 10.2.0
FontConfig 2.15.0
libcurl/8.14.1 OpenSSL/3.5.1 zlib/1.3.1 brotli/1.1.0 zstd/1.5.7 libidn2/2.3.8 libpsl/0.21.2 libssh2/1.11.1 nghttp2/1.64.0 nghttp3/1.8.0 librtmp/2.3 OpenLDAP/2.6.10

Platform: Debian GNU/Linux 13 (trixie), 64 bit, Little endian, wxGTK, X11, cinnamon, x11
OpenGL: Intel, Mesa Intel(R) HD Graphics 2500 (IVB GT1), 4.2 (Compatibility Profile) Mesa 25.0.7-2

Build Info:
Date: Oct 11 2025 10:45:10
wxWidgets: 3.2.8 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.83.0
OCC: 7.8.1
Curl: 8.14.1
ngspice: 44.2
Compiler: GCC 14.2.0 with C++ ABI 1019
KICAD_IPC_API=ON

Locale:
Lang: en_IN
Enc: UTF-8
Num: 1,234.5
Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)

2

I’m having a similar issue on Windows 11. Switching to backup graphics in the Scheme Editor settings helps. RX 6400 card.

3

The fall back graphics option in schematic editor seems better and drawing wires with it is somewhat responsive than accelerated graphics option. OpenGL should accelerate the graphics rendering with hardware but its not.

4

I checked the same behavior in the night version…

5

I also ran a small test on Linux Mint 22 Flatpack 9.0.6, it works significantly faster than in the video, the hardware is the same

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6

Did you run the schematic editor in Linux Mint with accelerated graphics or fallback graphics?

7

I ran it with accelerated graphics on the RX 6400.

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8

Are there any settings for version 9 that aren’t obvious and affect the movement speed? Or is this a bug?

9

Well at least on Win11, the lag seems better that it was in 7.0.9.

10

It’s not clear why the latency decreases when accelerated graphics is turned off?

11

Your video looks similar to how it works on my machine. I don’t experience this as a problem. Everything seems to work just fine. Should I be worried?

12

With display refresh rate changed to 60 Hz:

When KiCad and OBS are both running on Intel(R) Iris(R) Xe Graphics GPU, I see no lag in both Accelerated and Fallback:

When OBS is not running, there is some lag, but it’s consistent between Accelerated and Fallback.

When KiCad is running on NVIDIA GeForce RTX 3070 Laptop GPU, there’s a significant lag in Accelerated mode. OBS doesn’t affect it:

I suspect it’s some weird OS+Driver interaction which probably throttles the GPUs

1 Like
13

One might assume this behavior is platform-specific, but a similar situation is observed on Linux. Different drivers, different platforms, but the lag remains. I tested it on an RX6400 with the latest available driver and on a laptop with an AMD processor. The lag remains. It’s a mystery…

14

Setting V-sync to Off in NVIDIA control panel completely removes the lag when using the NVIDIA GPU. The KiCad crosshair moves even faster than Windows’s cursor.

image
image959×701 38.2 KB

I suspect V-sync is just implemented poorly in this config.

When using Intel GPU, there’s still a small lag, even if V-sync is disabled in KiCad code. Unless OBS is running, which keeps the GPU from throttling, I presume.

1 Like
15

I don’t know for sure if it is a problem. Perhaps a long time user of KiCad can answer that question. I assumed the lag is due to using a intel iGPU i.e onboard graphics and using an older intel i5 quad core CPU. It seems people with GPUs also experienced this issue.

Ideally, there should be no lag between the mouse pointer and the line being drawn or a symbol being moved with mouse pointer or while placing the symbol with mouse on the schematic. I couldn’t tell if all PCB tools have this delay.

The same lag behavior is also seen on windows which probably has latest and correct display driver installed.

16

You didn’t seem to try drawing a wire or placing a symbol on the schematic. My mouse pointer moves same as yours however there is some lag in drawing wires with the Wire icon on right toolbar and placing symbols with the symbol icon on right toolbar. Other users have also experienced the same.

17

I don’t see any difference on my PC.

18

We need to try to file a bug report, but it’s not clear how to formulate it with an example, since it’s unclear under what conditions it occurs. One thing is clear: it occurs on all three main video cards from different manufacturers and on different platforms. Any ideas?

19

The latency may vary across platforms, but it’s definitely there. I’ll try disabling vertical sync, but I’m not sure Linux has such a setting.

20

Try

vblank_mode=0 kicad
1 Like