Returning to PHP development after an extended break, I encountered an unexpected latency issue in my WAMP environment. Simple requests that previously executed instantly now take 5+ seconds to serve a basic 300B HTML page, despite minimal CPU usage (0-2%) and idle Apache processes.

First, verify your WAMP components:

// Check running services
netstat -ano | findstr :80
tasklist /svc | findstr httpd
wmic process where name="httpd.exe" get CommandLine

Modern Apache installations often include DNS lookups that can introduce latency. Check your httpd.conf:

# Disable reverse DNS lookups
HostnameLookups Off
# Add this to prevent delays
EnableMMAP off
EnableSendfile off

For WAMP on Windows, these adjustments help:

# In httpd.conf
AcceptFilter http none
AcceptFilter https none
# Adjust thread priority
Win32DisableAcceptEx

Inspect php.ini for problematic settings:

; Disable unnecessary modules
disable_functions = "pcntl_alarm,pcntl_fork,pcntl_waitpid"
; Adjust realpath cache
realpath_cache_size = 256k
realpath_cache_ttl = 600

Windows TCP stack settings affect localhost performance:

# Run in elevated CMD
netsh int tcp set global autotuninglevel=restricted
netsh interface ipv4 set dynamicport tcp start=49152 num=16384

For WAMP users, try these additional steps:

1. Right-click WAMP icon → Tools → Reinstall services
2. Check "Put Online" status
3. Test with different PHP versions

Add this to php.ini for profiling:

[xdebug]
xdebug.profiler_enable_trigger = 1
xdebug.profiler_output_dir = "c:/wamp/tmp"
xdebug.profiler_output_name = "cachegrind.out.%t"

Verify if the issue is Apache-specific:

# Test raw TCP response time
echo -e "GET / HTTP/1.1\\r\\nHost: localhost\\r\\n\\r\\n" | nc localhost 80
# Or using PowerShell:
Measure-Command { Invoke-WebRequest http://localhost }

• Verify hosts file entry: 127.0.0.1 localhost
• Disable IPv6 in Apache if unused
• Check for conflicting .htaccess rules
• Test with fresh virtual host configuration

---

After returning to my WAMP development environment following an extended break, I encountered a perplexing issue: simple PHP pages that should load instantly were taking 5+ seconds to respond, despite minimal system resource usage. The symptoms were particularly puzzling:

• 300B HTML files taking 5 seconds to serve
• Apache httpd processes showing 0% CPU usage
• Overall system load at 0-2%

First, I verified the basic configuration wasn't causing the delay:

# Check if this is a DNS resolution issue
ping localhost

# Test raw Apache response time without PHP
curl -I http://localhost/test.html

When these basic tests confirmed the latency was specific to PHP processing, I dug deeper into the WAMP stack configuration.

These are the most frequent causes I've encountered for localhost latency issues:

1. IPv6 vs IPv4 resolution: Windows sometimes prefers IPv6 for localhost
2. Apache/PHP module configuration: Especially with newer PHP versions
3. Windows hosts file issues
4. XDebug or other debugging tools inadvertently enabled

After extensive testing, the solution was in the Windows hosts file. Here's how to implement it:

# Open Notepad as administrator
# Edit C:\Windows\System32\drivers\etc\hosts
# Ensure these lines exist and are uncommented:

127.0.0.1       localhost
::1             localhost

Additionally, I modified my httpd.conf with these performance tweaks:

# In Apache httpd.conf
EnableMMAP off
EnableSendfile off
HostnameLookups off

# For PHP (php.ini)
realpath_cache_size = 4096K
realpath_cache_ttl = 600
opcache.enable=1

To test if the changes worked, I created a simple benchmark script:

<?php
$start = microtime(true);
echo "Test response";
$end = microtime(true);
file_put_contents('perf.log', ($end-$start).PHP_EOL, FILE_APPEND);
?>

After implementing these changes, response times dropped from 5000ms to consistent sub-10ms performance.

For developers wanting to squeeze every millisecond from their WAMP setup:

• Disable unused Apache modules (mod_rewrite, mod_ssl if not needed)
• Adjust ThreadsPerChild and MaxRequestWorkers in httpd-mpm.conf
• Set PHP's realpath_cache_size appropriately for your project size
• Consider using WAMP alternatives like Laragon for better performance

The key takeaway: localhost slowness is almost always a configuration issue rather than a hardware limitation, even when system metrics don't immediately reveal the cause.