Syncthing makes my computer slow

Greetings! I used Syncthing on about 50 GB of files in 5 different folders on Linux. Every time the service ran a scan for file changes, it would make my laptop very slow. Apps would sometimes lag for over a second.

I suspect the Linux scheduling is made to share memory and CPU. Syncthing would slow down the laptop through the high disk utilization.

It has lead me to a point where I stopped using the service all together. Is there a way to resolve this?

Thanks!

Could you provide details about the hardware in your laptop? (e.g., hard drive or SSD, system RAM, CPU, Linux version, etc.)

Does the 50GB of files consist of lots of small files?

My laptop is a bit old, but I did have exactly the same experience on another similar laptop. CPU i7-6600U, 16 GB of RAM and SSD, you can find more details below.

          ▗▄▄▄       ▗▄▄▄▄    ▄▄▄▖            miki@nixtop 
          ▜███▙       ▜███▙  ▟███▛            ----------- 
           ▜███▙       ▜███▙▟███▛             OS: NixOS 23.05pre442137.37b97ae3dd7 (Stoat) x86_64 
            ▜███▙       ▜██████▛              Host: HP 80FA 
     ▟█████████████████▙ ▜████▛     ▟▙        Kernel: 5.15.86 
    ▟███████████████████▙ ▜███▙    ▟██▙       Uptime: 1 day, 17 hours, 17 mins 
           ▄▄▄▄▖           ▜███▙  ▟███▛       Packages: 2639 (nix-system) 
          ▟███▛             ▜██▛ ▟███▛        Shell: bash 5.1.16 
         ▟███▛               ▜▛ ▟███▛         Resolution: 1920x1080 
▟███████████▛                  ▟██████████▙   DE: GNOME 43.2 (Wayland) 
▜██████████▛                  ▟███████████▛   WM: Mutter 
      ▟███▛ ▟▙               ▟███▛            WM Theme: Adwaita 
     ▟███▛ ▟██▙             ▟███▛             Theme: Adwaita-dark [GTK2/3] 
    ▟███▛  ▜███▙           ▝▀▀▀▀              Icons: Adwaita [GTK2/3] 
    ▜██▛    ▜███▙ ▜██████████████████▛        Terminal: kgx 
     ▜▛     ▟████▙ ▜████████████████▛         CPU: Intel i7-6600U (4) @ 3.400GHz 
           ▟██████▙       ▜███▙               GPU: Intel Skylake GT2 [HD Graphics 520] 
          ▟███▛▜███▙       ▜███▙              Memory: 3991MiB / 15889MiB 
         ▟███▛  ▜███▙       ▜███▙
         ▝▀▀▀    ▀▀▀▀▘       ▀▀▀▘                                     
                                                                      

Although your laptop’s CPU is older, it’s got plenty of horsepower plus there’s plenty of RAM for Syncthing. Unless the SSD is dying, it doesn’t appear that lack of hardware resources is the issue (for comparison, my laptop has a i5-4200U / 8GB RAM / SSD.).

You’re running a pretty recent Linux kernel which has an overhauled process scheduler. Combined with the SSD (which likely supports NCQ), everything says Syncthing should have no issues.

What’s the contents 50 GB of files like? Hundreds of thousands of tiny files that change frequently, a few hundred large files that change once and a while, or something else?