Multithread not working for all operations?

[nuthinking]

I'm trying to convert a video to a version with a keyframe on every frame. I use this command:

ffmpeg -i original.mp4 -r 30 -g 30 video.mp4

In the Playground it works only with single thread but it takes 10 minutes to convert a medium size video. If I try multi-thread I get this message in the console:

[mov,mp4,m4a,3gp,3g2,mj2 @ 0xdec250] st: 0 edit list: 1 Missing key frame while searching for timestamp: 1000
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xdec250] st: 0 edit list 1 Cannot find an index entry before timestamp: 1000.

Full console:

ffmpeg version 5.1.4 Copyright (c) 2000-2023 the FFmpeg developers
  built with emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.40 (5c27e79dd0a9c4e27ef2326841698cdd4f6b5784)
  configuration: --target-os=none --arch=x86_32 --enable-cross-compile --disable-asm --disable-stripping --disable-programs --disable-doc --disable-debug --disable-runtime-cpudetect --disable-autodetect --nm=emnm --ar=emar --ranlib=emranlib --cc=emcc --cxx=em++ --objcc=emcc --dep-cc=emcc --extra-cflags='-I/opt/include -O3 -msimd128 -sUSE_PTHREADS -pthread' --extra-cxxflags='-I/opt/include -O3 -msimd128 -sUSE_PTHREADS -pthread' --enable-gpl --enable-libx264 --enable-libx265 --enable-libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libopus --enable-zlib --enable-libwebp --enable-libfreetype --enable-libfribidi --enable-libass --enable-libzimg
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xdec250] st: 0 edit list: 1 Missing key frame while searching for timestamp: 1000
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xdec250] st: 0 edit list 1 Cannot find an index entry before timestamp: 1000.
Guessed Channel Layout for Input Stream #0.1 : stereo
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'a9a37f8ccf8dbb5d0b5cb55109b15f58.mp4':
  Metadata:
    major_brand     : XAVC
    minor_version   : 16785407
    compatible_brands: XAVCmp42iso2
    creation_time   : 2024-03-31T02:16:23.000000Z
  Duration: 00:00:39.84, start: 0.000000, bitrate: 18531 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/bt709/iec61966-2-4, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 15606 kb/s, 25 fps, 25 tbr, 25k tbn (default)
    Metadata:
      creation_time   : 2024-03-31T02:16:23.000000Z
      handler_name    : Video Media Handler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding
    Side data:
      displaymatrix: rotation of 90.00 degrees
  Stream #0:1[0x2](und): Audio: pcm_s16be (twos / 0x736F7774), 48000 Hz, stereo, s16, 1536 kb/s (default)
    Metadata:
      creation_time   : 2024-03-31T02:16:23.000000Z
      handler_name    : Sound Media Handler
      vendor_id       : [0][0][0][0]
  Stream #0:2[0x3](und): Data: none (rtmd / 0x646D7472), 1024 kb/s (default)
    Metadata:
      creation_time   : 2024-03-31T02:16:23.000000Z
      handler_name    : Timed Metadata Media Handler
      timecode        : 17:02:22:02
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (pcm_s16be (native) -> aac (native))
[libx264 @ 0xdf3bc0] using SAR=1/1
[libx264 @ 0xdf3bc0] using cpu capabilities: none!
[libx264 @ 0xdf3bc0] profile High, level 4.0, 4:2:0, 8-bit
[libx264 @ 0xdf3bc0] 264 - core 164 - H.264/MPEG-4 AVC codec - Copyleft 2003-2022 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=30 keyint_min=3 scenecut=40 intra_refresh=0 rc_lookahead=30 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00

Is there any hope to get a faster operation of this kind? Thanks!