Performance issue on some webpages - how to analyse

[bringha]

Hello together,

I am facing currently on some web pages a very poor performance up to that they are not be shown at all in any browser of the network (LAN). Example ist eg www.lumas.de or also postbank.de. Commonality to these sites is

• widespread use of large java script files obtained from many different URLs
• Many Banner and images

but others with the same pattern work fine.

My Opnsense runs in a XEN VM. I am using unbound on the opnsense box as primary DNS resolver, being connected to OpenDNS and Google DNS Servers. Config on all of the opnsense box interfaces is

Code: [Select]

xn0: flags=8a43<UP,BROADCAST,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=503<RXCSUM,TXCSUM,TSO4,LRO>
(...)
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet manual
status: active

No pecularity in the logs of the opnsense box. I correlate this behavior time wise  to the update to 16.1.14, getting slowly worse over time.

My config is a fritz box accessing the internet and being connected to the WAN interface in opnsense, running dual stack ipv4 and ipv6. All clients in the LAN (mobile and fixed) showing the same behavior for the same sites with the different browsers (Safari, Chrome, Firefox). Even if the problem page appears after a while, its mostly incomplete, elements are missing. I assumed an misconfig or anything like this in MTU, but so far I found no evidence for this ..

What I could find out so far:

• When I bypass opnsense and connect to the fritzbox directly, performance is fine
• When I switch off Javascript in the browser, then performance is also ok (but indeed not everything is shown)
• The progress bar for these pages hang for sometime several minutes and progress stepwise
• I randomly checked some of the URLs being embedded in the pages show pretty diverging DNS resolution time when resolved with unbound (22ms (normal) up to 340 ms) but not when resolved directly eg with google DNS server
• rebooting clients, deleting caches in the browser, rebooting opnsense did not change anything
• error monitor in safari indicates very long load times of some java scripts (eg postbank.js)

Has somebody an idea how such an issue can be systematically analysed further, eg with some diag tools on opnsense or client?

I am looking forward to any kind of ideas and tips.

Thanks for your support

Br br