firefox is slow and uses a lot of memory

From: Craig Leres <leres_at_freebsd.org>
Date: Thu, 01 Jul 2021 19:49:15 UTC 
Starting with firefox 89 or so, I've found it starts using a LOT of 
memory and actually makes the system sluggish and causes momentary X 
freezes. I have 32G of ram/swap, is it reasonable for firefox to use 15G?

		Craig

ice 95 % uname -a
FreeBSD ice.alameda.xse.com 12.2-RELEASE-p8 FreeBSD 12.2-RELEASE-p8 r18 
LBL  amd64


 >>>> top -osize

last pid: 71913;  load averages:  0.52,  0.53,  0.47    up 1+00:29:04 
12:46:04
215 processes: 2 running, 206 sleeping, 6 stopped, 1 zombie
CPU:  1.9% user,  0.0% nice,  0.3% system,  0.1% interrupt, 97.7% idle
Mem: 2931M Active, 3479M Inact, 1874M Laundry, 19G Wired, 1192M Buf, 
4116M Free
ARC: 13G Total, 3822M MFU, 8686M MRU, 172K Anon, 270M Header, 553M Other
      11G Compressed, 81G Uncompressed, 7.38:1 Ratio
Swap: 32G Total, 32G Free

   PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU 
COMMAND
63858 leres        35  20    0    15G   506M select   7   0:40   0.08% 
firefox
  3610 leres         3  20    0  6268M    61M select   2   4:54   1.00% Xorg
  3159 telegraf     19  23    0  4926M    47M uwait    3   0:26   0.00% 
telegraf
63845 leres       125  20    0  4612M  1794M select   7  18:49   4.61% 
firefox
33553 leres        60  20    0  4579M  2077M CPU2     2   9:18   3.10% 
thunderb
63859 leres        34  20    0  2916M   559M select   3   1:11   0.08% 
firefox
63857 leres        34  20    0  2812M   466M select   0   2:00   0.18% 
firefox
63850 leres        37  20    0  2723M   377M select   2   1:51   0.24% 
firefox
63849 leres        34  20    0  2708M   394M select   3   1:05   0.02% 
firefox
63856 leres        34  20    0  2608M   275M select   6   0:30   0.01% 
firefox
63861 leres        34  20    0  2491M   189M select   6   0:05   0.05% 
firefox
63847 leres        34  20    0  2471M   171M select   1   0:04   0.05% 
firefox
70198 leres        27  20    0  2436M   142M select   5   0:01   0.05% 
firefox
63860 leres        26  20    0  2422M   130M select   2   0:01   0.00% 
firefox
  3132 influxd      18  52    0   997M   185M uwait    2   6:16   0.06% 
influxd
  3214 root          6  20    0   510M   491M select   0   2:38   0.19% 
pcscd
  2897 bind         26  52    0   349M   281M sigwai   0   0:15   0.00% 
named
22334 www           4  52    0   108M    77M select   3   0:02   0.00% httpd