top / htop                # Process monitoring
vmstat 1                  # Memory statistics
iostat -x 1               # Disk I/O
sar -n DEV 1              # Network statistics
perf top                  # CPU profiling

# /etc/sysctl.d/99-performance.conf
vm.swappiness = 10
net.core.somaxconn = 65535
net.ipv4.tcp_max_syn_backlog = 65535
fs.file-max = 2097152
vm.dirty_ratio = 40
vm.dirty_background_ratio = 10

# /etc/security/limits.conf
* soft nofile 65535
* hard nofile 65535
* soft nproc 65535
* hard nproc 65535

# Change scheduler
echo noop > /sys/block/sda/queue/scheduler

# Enable trim for SSDs
fstrim -av

# Increase buffers
sysctl -w net.core.rmem_max=134217728
sysctl -w net.core.wmem_max=134217728