Most popular speedup sysctl options for Proxmox. Put in /etc/sysctl.d/

sysctl-proxmox-tune.conf

###
# Proxmox or other server kernel params cheap tune and secure.
# Try it if you have heavy load on server - network or memory / disk.
# No harm assumed but keep your eyes open.
#
# @updated: 2020-02-06 - more params used, adjust some params values, more comments on params
# Origin https://gist.github.com/sergey-dryabzhinsky/bcc1a15cb7d06f3d4606823fcc834824
# @updated: 2023-12-21 - To test with proxmox v8
# # update: https://gist.github.com/linuxmalaysia/7ba3ded2dd3ec7f2491e549e6dcd73ec

### NETWORK ###

# Timeout broken connections faster (amount of time to wait for FIN)
net.ipv4.tcp_fin_timeout = 10

# Wait a maximum of 5 * 2 = 10 seconds in the TIME_WAIT state after a FIN, to handle
# any remaining packets in the network.
# load module nf_contrack if needed
### Missing in proxmox8 - Haris
####net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 5

# Keepalive optimizations
# By default, the keepalive routines wait for two hours (7200 secs) before sending the first keepalive probe,
# and then resend it every 75 seconds. If no ACK response is received for 9 consecutive times, the connection is marked as broken.
# The default values are: tcp_keepalive_time = 7200, tcp_keepalive_intvl = 75, tcp_keepalive_probes = 9
# We would decrease the default values for tcp_keepalive_* params as follow:
# Disconnect dead TCP connections after 10 minutes
net.ipv4.tcp_keepalive_time = 600
# Determines the wait time between isAlive interval probes (reduce from 75 sec to 15)
net.ipv4.tcp_keepalive_intvl = 15
# Determines the number of probes before timing out (reduce from 9 sec to 5 sec)
net.ipv4.tcp_keepalive_probes = 5

# allow that much active connections
net.core.somaxconn = 256000

# Protection from SYN flood attack.
net.ipv4.tcp_syncookies = 1
# Only retry creating TCP connections twice
# Minimize the time it takes for a connection attempt to fail
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_orphan_retries = 2

# Handle SYN floods and large numbers of valid HTTPS connections
net.ipv4.tcp_max_syn_backlog = 40000

# Increase the length of the network device input queue
net.core.netdev_max_backlog = 50000

# Increase ephermeral IP ports
# https://docs.oracle.com/en/database/oracle/oracle-database/19/cwlin/setting-udp-and-tcp-kernel-parameters-manually.html#GUID-F94545C8-7695-4866-89B0-F32651CD3658
net.ipv4.ip_local_port_range = 1024    65500

# Broken combined
net.ipv4.tcp_tw_reuse = 0
#net.ipv4.tcp_tw_recycle = 0

# https://www.serveradminblog.com/2011/02/neighbour-table-overflow-sysctl-conf-tunning/
net.ipv4.neigh.default.gc_thresh1 = 1024
net.ipv4.neigh.default.gc_thresh2 = 2048
net.ipv4.neigh.default.gc_thresh3 = 4096

# http://www.opennet.ru/opennews/art.shtml?num=44945
net.ipv4.tcp_challenge_ack_limit = 9999

# Don't slow network - save congestion window after idle
# https://github.com/ton31337/tools/wiki/tcp_slow_start_after_idle---tcp_no_metrics_save-performance
net.ipv4.tcp_slow_start_after_idle = 0

# If we must send packets at first place, but throughput is on second
net.ipv4.tcp_low_latency = 1

#### PVE ####

# Allow a high number of timewait sockets
net.ipv4.tcp_max_tw_buckets = 2000000

# PVE 3
#net.ipv4.tcp_max_tw_buckets_ub = 65000


# Increase Linux autotuning TCP buffer limits
net.ipv4.tcp_wmem = 4096        65536   16777216
net.ipv4.tcp_rmem = 4096        87380   16777216
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.optmem_max = 65536


# If your servers talk UDP, also up these limits
net.ipv4.udp_rmem_min = 8192
net.ipv4.udp_wmem_min = 8192

# Sockets/UDP query length
net.unix.max_dgram_qlen = 1024

# http://vds-admin.ru/unix-linux/oshibki-v-dmesg-vida-nfconntrack-table-full-dropping-packet
# load module nf_contrack if needed
## Not in v8 - Haris
###net.netfilter.nf_conntrack_max = 1048576
###net.nf_conntrack_max = 1048576


### MEMORY ###

# do less swap but not disable it
vm.swappiness = 1

# allow application request allocation of virtual memory
# more than real RAM size (or OpenVZ/LXC limits)
#####vm.overcommit_memory = 1

# https://major.io/2008/12/03/reducing-inode-and-dentry-caches-to-keep-oom-killer-at-bay/
vm.vfs_cache_pressure = 500

# time in  centi-sec. i.e. 100 points = 1 second
# delayed write of dirty data
vm.dirty_writeback_centisecs = 3000
# flush from memory old dirty data
vm.dirty_expire_centisecs = 18000

##
# Adjust vfs cache
# https://lonesysadmin.net/2013/12/22/better-linux-disk-caching-performance-vm-dirty_ratio/
# Decriase dirty cache to faster flush on disk
vm.dirty_background_ratio = 5
vm.dirty_ratio = 10

#### PVE 3 ####

# Only on Proxmox 3.x with OpenVZ
#ubc.dirty_ratio = 20
#ubc.dirty_background_ratio = 10

# Isolate page cache for VPS.
#ubc.pagecache_isolation = 1

### FileSystem ###

##
# Fix: Failed to allocate directory watch: Too many open files
#      in Proxmox 5 + LXC
#      And VM with Bitrix
#      == alot of files

fs.inotify.max_user_instances = 16777216
fs.inotify.max_queued_events = 32000
fs.inotify.max_user_watches = 64000


### Security ###

# http://www.opennet.ru/opennews/art.shtml?num=47792
kernel.unprivileged_bpf_disabled=1

# http://www.opennet.ru/opennews/art.shtml?num=49135
### Not in v8 - Haris
###net.ipv4.ipfrag_high_thresh=262144
net.ipv4.ipfrag_low_thresh=196608
### Not in v8 - Haris
###net.ipv6.ip6frag_high_thresh=262144
net.ipv6.ip6frag_low_thresh=196608

# http://www.opennet.ru/opennews/art.shtml?num=50889
net.ipv4.tcp_sack = 0

# Prevent TIME_WAIT attak.
net.ipv4.tcp_rfc1337 = 1


### OTHER ###

# https://tweaked.io/guide/kernel/
# Don't migrate processes between CPU cores too often
### Not in v8 - Haris
####kernel.sched_migration_cost_ns = 5000000
# Kernel >= 2.6.38 (ie Proxmox 4+)
kernel.sched_autogroup_enabled = 0
vm.nr_hugepages = 1

# https://www.cyberciti.biz/cloud-computing/increase-your-linux-server-internet-speed-with-tcp-bbr-congestion-control/
# http://lwn.net/Articles/616241/
# Set the default queueing discipline for network devices
net.core.default_qdisc = fq_codel

# Enable TCP BBR congestion control
net.ipv4.tcp_congestion_control=bbr

# Enable TCP MTU probing
net.ipv4.tcp_mtu_probing=1

root@myserver:/etc/sysctl.d# cat README.sysctl
Kernel system variables configuration files

Files found under the /etc/sysctl.d directory that end with .conf are
parsed within sysctl(8) at boot time. If you want to set kernel variables
you can either edit /etc/sysctl.conf or make a new file.

The filename isn't important, but don't make it a package name as it may clash
with something the package builder needs later. It must end with .conf though.

My personal preference would be for local system settings to go into
/etc/sysctl.d/local.conf but as long as you follow the rules for the names
of the file, anything will work. See sysctl.conf(8) man page for details
of the format.

After making any changes, please run "service procps force-reload" (or, from
a Debian package maintainer script "deb-systemd-invoke restart procps.service").

To check status:

systemctl status systemd-sysctl.service