A new symptom. While I'm working with NetBeans the system very often freezes randomly. Only reboot helps. I see next data in log:
[   235.747] (EE) BUG: triggered 'if (glyph->refcnt == 0)'
[   235.748] (EE) BUG: ../../../../render/glyph.c:252 in FreeGlyph()
[   235.748] (EE) 
[   235.748] (EE) Backtrace:
[   235.748] (EE) 0: /usr/lib/xorg/Xorg (AddTraps+0x4e3b) [0x5590352dce3b]
[   235.748] (EE) 1: /usr/lib/xorg/Xorg (SendErrorToClient+0x354) [0x559035205144]
[   235.748] (EE) 2: /usr/lib/xorg/Xorg (InitFonts+0x3b4) [0x5590352091f4]
[   235.749] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7f6d6bb0c083]
[   235.749] (EE) 4: /usr/lib/xorg/Xorg (_start+0x2e) [0x5590351f2ace]
[   235.749] (EE) 
[   235.749] (EE) BUG: triggered 'if (glyph->refcnt == 0)'
[   235.749] (EE) BUG: ../../../../render/glyph.c:252 in FreeGlyph()
[   235.749] (EE) 
[   235.749] (EE) Backtrace:
[   235.749] (EE) 0: /usr/lib/xorg/Xorg (AddTraps+0x4e3b) [0x5590352dce3b]
[   235.749] (EE) 1: /usr/lib/xorg/Xorg (SendErrorToClient+0x354) [0x559035205144]
[   235.749] (EE) 2: /usr/lib/xorg/Xorg (InitFonts+0x3b4) [0x5590352091f4]
[   235.750] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7f6d6bb0c083]
[   235.750] (EE) 4: /usr/lib/xorg/Xorg (_start+0x2e) [0x5590351f2ace]
[   235.750] (EE) 
[   235.750] (EE) 
[   235.750] (EE) Backtrace:
[   235.751] (EE) 0: /usr/lib/xorg/Xorg (OsLookupColor+0x13c) [0x559035366fdc]
[   235.751] (EE) 1: /lib/x86_64-linux-gnu/libpthread.so.0 (funlockfile+0x60) [0x7f6d6bcf0420]
[   235.752] (EE) 2: /lib/x86_64-linux-gnu/libc.so.6 (gsignal+0xcb) [0x7f6d6bb2b00b]
[   235.752] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (abort+0x12b) [0x7f6d6bb0a859]
[   235.753] (EE) 4: /lib/x86_64-linux-gnu/libc.so.6 (__fsetlocking+0x42e) [0x7f6d6bb7526e]
[   235.754] (EE) 5: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0x54c) [0x7f6d6bb7d2fc]
[   235.754] (EE) 6: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0xd28) [0x7f6d6bb7dad8]
[   235.755] (EE) 7: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0x2230) [0x7f6d6bb7efe0]
[   235.755] (EE) 8: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0x4172) [0x7f6d6bb80f22]
[   235.756] (EE) 9: /lib/x86_64-linux-gnu/libc.so.6 (realloc+0x2d6) [0x7f6d6bb83156]
[   235.756] (EE) 10: /usr/lib/xorg/Xorg (ReadRequestFromClient+0x4ab) [0x559035365e8b]
[   235.757] (EE) 11: /usr/lib/xorg/Xorg (SendErrorToClient+0x2ed) [0x5590352050dd]
[   235.757] (EE) 12: /usr/lib/xorg/Xorg (InitFonts+0x3b4) [0x5590352091f4]
[   235.758] (EE) 13: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7f6d6bb0c083]
[   235.758] (EE) 14: /usr/lib/xorg/Xorg (_start+0x2e) [0x5590351f2ace]
[   235.759] (EE) 
[   235.759] (EE) 
Fatal server error:
[   235.759] (EE) Caught signal 6 (Aborted). Server aborting
[   235.759] (EE) 
[   235.759] (EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.x.org
 for help. 
[   235.760] (EE) Please also check the log file at "/home/axenic/.local/share/xorg/Xorg.0.log" for additional information.
[   235.760] (EE) 
[   235.760] (II) AIGLX: Suspending AIGLX clients for VT switch

Or this:

[  1036.721] (EE) BUG: triggered 'if (glyph->refcnt == 0)'
[  1036.721] (EE) BUG: ../../../../render/glyph.c:252 in FreeGlyph()
[  1036.721] (EE) 
[  1036.721] (EE) Backtrace:
[  1036.722] (EE) 0: /usr/lib/xorg/Xorg (AddTraps+0x4e3b) [0x5570de00de3b]
[  1036.723] (EE) 1: /usr/lib/xorg/Xorg (SendErrorToClient+0x354) [0x5570ddf36144]
[  1036.723] (EE) 2: /usr/lib/xorg/Xorg (InitFonts+0x3b4) [0x5570ddf3a1f4]
[  1036.723] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7f317a306083]
[  1036.723] (EE) 4: /usr/lib/xorg/Xorg (_start+0x2e) [0x5570ddf23ace]
[  1036.723] (EE) 
[  1036.723] (EE) 
[  1036.723] (EE) Backtrace:
[  1036.723] (EE) 0: /usr/lib/xorg/Xorg (OsLookupColor+0x13c) [0x5570de097fdc]
[  1036.724] (EE) 1: /lib/x86_64-linux-gnu/libpthread.so.0 (funlockfile+0x60) [0x7f317a4ea420]
[  1036.724] (EE) 2: /lib/x86_64-linux-gnu/libc.so.6 (gsignal+0xcb) [0x7f317a32500b]
[  1036.725] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (abort+0x12b) [0x7f317a304859]
[  1036.725] (EE) 4: /lib/x86_64-linux-gnu/libc.so.6 (__fsetlocking+0x42e) [0x7f317a36f26e]
[  1036.725] (EE) 5: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0x54c) [0x7f317a3772fc]
[  1036.726] (EE) 6: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0xd28) [0x7f317a377ad8]
[  1036.726] (EE) 7: /lib/x86_64-linux-gnu/libc.so.6 (pthread_attr_setschedparam+0x2ed3) [0x7f317a379c83]
[  1036.726] (EE) 8: /lib/x86_64-linux-gnu/libc.so.6 (__libc_calloc+0x85) [0x7f317a37db95]
[  1036.730] (EE) 9: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so (radeon_drm_winsys_create+0x176878) [0x7f3178a79d18]
[  1036.730] (EE) 10: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so (radeon_drm_winsys_create+0x17778d) [0x7f3178a7ac2d]
[  1036.731] (EE) 11: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so (__driDriverGetExtensions_d3d12+0x5d36f) [0x7f31781e19df]
[  1036.732] (EE) 12: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so (__driDriverGetExtensions_d3d12+0x20b3af) [0x7f317838fa1f]
[  1036.732] (EE) 13: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so (__driDriverGetExtensions_d3d12+0x20e2e9) [0x7f3178392959]
[  1036.733] (EE) 14: /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so (__driDriverGetExtensions_d3d12+0x214029) [0x7f3178398699]
[  1036.733] (EE) 15: /usr/lib/xorg/modules/libglamoregl.so (glamor_create_gc+0x101fc) [0x7f31702d533c]
[  1036.733] (EE) 16: /usr/lib/xorg/modules/libglamoregl.so (glamor_create_gc+0x2390) [0x7f31702c74d0]
[  1036.733] (EE) 17: /usr/lib/xorg/Xorg (DamageRegionAppend+0xb97) [0x5570de018e07]
[  1036.733] (EE) 18: /usr/lib/xorg/Xorg (AddTraps+0x3a5f) [0x5570de00ca5f]
[  1036.734] (EE) 19: /usr/lib/xorg/Xorg (SendErrorToClient+0x354) [0x5570ddf36144]
[  1036.734] (EE) 20: /usr/lib/xorg/Xorg (InitFonts+0x3b4) [0x5570ddf3a1f4]
[  1036.734] (EE) 21: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7f317a306083]
[  1036.734] (EE) 22: /usr/lib/xorg/Xorg (_start+0x2e) [0x5570ddf23ace]
[  1036.734] (EE) 
[  1036.734] (EE) 
Fatal server error:
[  1036.734] (EE) Caught signal 6 (Aborted). Server aborting
[  1036.734] (EE) 
[  1036.734] (EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.x.org
 for help. 
[  1036.734] (EE) Please also check the log file at "/home/iq/.local/share/xorg/Xorg.0.log" for additional information.
[  1036.734] (EE) 
[  1036.735] (II) AIGLX: Suspending AIGLX clients for VT switch