LCP increase after >=13.5.5-canary.1

[teh23]

13.5.5-canary.0:

13.5.5-canary.1:

14.0.1:

Performance tab:

13.5.5-canary.0:

14.0.1:

Does anyone have any idea what could be the cause of such a spike? Or maybe someone else had a similar issue?

[icyJoseph]

The lighthouse runs have a breakdown of the 4 parts involved in LCP:

Something like:

LCP sub-part	% of LCP
Time to first byte (TTFB)	~40%
Resource load delay	<10%
Resource load time	~40%
Element render delay	<10%
TOTAL	100%

Could you posts yours?

[teh23]

Sure!

13.5.5-canary.0:

Phase	% of LCP	Timing
TTFB	14%	450 ms
Load Delay	0%	0 ms
Load Time	0%	0 ms
Render Delay	86%	2,720 ms

14.0.1:

Phase	% of LCP	Timing
TTFB	10%	450 ms
Load Delay	0%	0 ms
Load Time	0%	0 ms
Render Delay	90%	4,100 ms

[markoleavy]

@teh23 have you found any solution? I also have really long render delay. As mention on discussion 58982 it might be because of the async loading of next javascripts.

PHASE	% of LCP	Timing
TTFB	12%	630 ms
Load Delay	11%	620 ms
Load Time	2%	120 ms
Render Delay	75%	4.020 ms

[teh23]

@markoleavy We haven't found a solution yet, we are still on 13.5.4 with this project. Also we had another project and we were facing the same issue with high render delay. Both sites are static and have a lot of data loading from rsc into client component maybe it is something in this direction.

I tested this async script by editing .next/server/app/index.html no effect at all

[markoleavy]

Did you switched all of the next scripts to defer?

[markoleavy]

Just tried to switch back to 13.5.4 and my LCP moved from 5-6 seconds to 2.7.
I can say there's a huge difference in the number of scripts in the doc's head between the two version:
Next-related scripts on 13.5.4:

<script src="/_next/static/chunks/afbc845c-5d36f2573a2b591d.js" async="" crossorigin=""></script>
<script src="/_next/static/chunks/6231-4e14ec391dfe872e.js" async="" crossorigin=""></script>
<script src="/_next/static/chunks/main-app-2635d5f757a6ff44.js" async="" crossorigin=""></script>Ï

On 14.1.0:

<script src="/_next/static/chunks/a130e3cb-d38efdea30cfec3b.js" async="" crossorigin=""></script>
<script src="/_next/static/chunks/4237-681d4002027859ea.js" async="" crossorigin=""></script>
<script src="/_next/static/chunks/main-app-c2a7c0b582017c36.js" async="" crossorigin=""></script>
<script src="/_next/static/chunks/4027-1c8e6416e910c85c.js" async=""></script>
<script src="/_next/static/chunks/827-dfe3f0537e505d05.js" async=""></script>
<script src="/_next/static/chunks/491-eb8a89f37ca70982.js" async=""></script>
<script src="/_next/static/chunks/3994-d0c60c9a80fbbe35.js" async=""></script>
<script src="/_next/static/chunks/1666-fb1ccf53037735e0.js" async=""></script>
<script src="/_next/static/chunks/app/layout-2f513177a25f9f4b.js" async=""></script>
<script src="/_next/static/chunks/7441-4a9201d8e11007e6.js" async=""></script>
<script src="/_next/static/chunks/4701-9a49f4b78f98791b.js" async=""></script>
<script src="/_next/static/chunks/6425-5f8926146141af22.js" async=""></script>
<script src="/_next/static/chunks/3302-ce60431bc4a5e281.js" async=""></script>
<script src="/_next/static/chunks/880-2311daad7a04e2f7.js" async=""></script>
<script src="/_next/static/chunks/59-163a4eeb14d23ebb.js" async=""></script>
<script src="/_next/static/chunks/6844-fdfec061e872d372.js" async=""></script>
<script src="/_next/static/chunks/2678-aa6ed48349311666.js" async=""></script>
<script src="/_next/static/chunks/4658-8fe48b577eae9c76.js" async=""></script>
<script src="/_next/static/chunks/5164-7d5b0ec5527c32ad.js" async=""></script>
<script src="/_next/static/chunks/8901-4134a0830ec14388.js" async=""></script>
<script src="/_next/static/chunks/8459-6467e41a2881881f.js" async=""></script>
<script src="/_next/static/chunks/177-e5113f7b1a8f45d4.js" async=""></script>
<script src="/_next/static/chunks/2515-c3ae39a4c6ef89f7.js" async=""></script>
<script src="/_next/static/chunks/5573-96e397d8f7a1ec69.js" async=""></script>
<script src="/_next/static/chunks/2657-2bbf3058b7ef121a.js" async=""></script>
<script src="/_next/static/chunks/2070-7dc1e116ca2fa6ca.js" async=""></script>
<script src="/_next/static/chunks/3907-09b53e2850808f41.js" async=""></script>
<script src="/_next/static/chunks/4330-5f52fc3593fe75a0.js" async=""></script>
<script src="/_next/static/chunks/app/(mainLayout)/%5B...slug%5D/page-01d01e70c91c2bbf.js" async=""></script>
<script src="/_next/static/chunks/1135-31a778a9d5e21b45.js" async=""></script>
<script src="/_next/static/chunks/app/(mainLayout)/layout-862838f48f69d244.js" async=""></script>
<script src="/_next/static/chunks/app/(mainLayout)/loading-1058ffc73dc90d15.js" async=""></script>

[JacobBSargent]

I'm dealing with a similar issue, up to 11 seconds! With "next": "^15.0.3",

Has there been any update here?

Phase	% of LCP	Timing
TTFB	5%	600 ms
Load Delay	0%	0 ms
Load Time	0%	0 ms
Render Delay	95%	11,730 ms