Facebook JS SDK breakdown

	A	B	C	D	E
1	Size (in bytes)	% total size	File	Notes	Extra notes
2	38288	9.56%	entry.js	Initialization	initialization / polyfills / module system
3	36007	8.99%	JSON3.js	Polyfill
4	23029	5.75%	sdk.UIServer.js	UI-related
5	13048	3.26%	sdk.Dialog.js	UI-related
6	11287	2.82%	IframePlugin.js	UI-related
7	9754	2.43%	URIBase.js	Utility
8	9714	2.42%	sdk.XFBML.IframeWidget.js	UI-related
9	8909	2.22%	sdk.XD.js	Utility
10	7929	1.98%	JSSDKCssConfig.js	UI-related
11	7501	1.87%	sdk.Auth.js	Auth
12	7073	1.77%	ApiClient.js	Network
13	6624	1.65%	sdk.XFBML.Name.js	UI-related
14	6391	1.60%	sdk.DialogUtils.js	UI-related
15	6001	1.50%	XDM.js	Utility
16	5502	1.37%	sdk.XFBML.Video.js	UI-related
17	5289	1.32%	sdk.DOM.js	Utility
18	5025	1.25%	FB.js	Initialization
19	4960	1.24%	sdk.Canvas.Plugin.js	UI-related	Only for "Canvas" apps
20	4900	1.22%	sdk.XFBML.Save.js	UI-related
21	4748	1.19%	XFBML.js	UI-related
22	4742	1.18%	sdk.XFBML.Quote.js	UI-related
23	3992	1.00%	sdk.XFBML.Comments.js	UI-related
24	3971	0.99%	sdk.Data.js	Network
25	3906	0.97%	ApiBatcher.js	Network
26	3725	0.93%	Flash.js	Utility	Flash!
27	3399	0.85%	UserAgent_DEPRECATED.js	Utility	Only used for old IE support!
28	3309	0.83%	sdk.init.js	Initialization
29	3290	0.82%	ES.js	Polyfill	Entry point for polyfills (including ES5 ones)
30	3287	0.82%	JSSDKConfig.js	Configuration	config file with ton of keys including options for payment-related stuff irrelevant to most sites
31	3154	0.79%	UnicodeUtils.js	Utility
32	2886	0.72%	PluginTags.js	UI-related	Config of XFBML tags mapped to options
33	2857	0.71%	Type.js	Utility
34	2822	0.70%	JSONRPC.js	Network
35	2796	0.70%	sdk.api.js	Network
36	2593	0.65%	legacy:fb.auth.js	Legacy	Handles deprecated ways of calling auth-related methods
37	2558	0.64%	sdk.Frictionless.js	UI-related
38	2548	0.64%	CORSRequest.js	Network
39	2537	0.63%	sdk.Query.js	Network
40	2516	0.63%	ES5StringPrototype.js	Polyfill
41	2498	0.62%	legacy:fb.xfbml.js	Legacy
42	2498	0.62%	sdk.ErrorHandler.js	Utility
43	2484	0.62%	Queue.js	Utility
44	2461	0.61%	legacy:fb.canvas.js	Legacy	canvas related
45	2406	0.60%	sdk.ui.js	UI-related
46	2350	0.59%	insertIframe.js	UI-related
47	2320	0.58%	sdk.UA.js	Utility	user-agent detection
48	2297	0.57%	sdk.Content.js	Utility
49	2190	0.55%	FlashRequest.js	Network/Utility	Flash for requests and/or XD
50	2134	0.53%	sdk.Cookie.js	Utility
51	2107	0.53%	ES5ArrayPrototype.js	Polyfill
52	2106	0.53%	DOMEventListener.js	Polyfill	(-ish)
53	2098	0.52%	sdk.createIframe.js	UI-related
54	2027	0.51%	sdk.Canvas.IframeHandling.js	Canvas
55	2024	0.51%	JSONPRequest.js	Network
56	2020	0.50%	ObservableMixin.js	Utility
57	1978	0.49%	sdk.Canvas.Prefetcher.js	Canvas
58	1953	0.49%	Base64.js	Polyfill	(-ish)
59	1942	0.48%	sdk.Helper.js	Utility
60	1933	0.48%	Assert.js	Utility
61	1917	0.48%	sdk.XFBML.Element.js	UI-related
62	1891	0.47%	sdk.XFBML.LoginButton.js	UI-related
63	1872	0.47%	sdk.Impressions.js	Analytics
64	1859	0.46%	sdk.Event.js	Utility
65	1818	0.45%	sdk.MBasicInitializer.js	Utility
66	1801	0.45%	ES6ArrayPrototype.js	Polyfill
67	1606	0.40%	ES6Array.js	Polyfill
68	1553	0.39%	sdk.Runtime.js	Initialization
69	1444	0.36%	ES7ArrayPrototype.js	Polyfill
70	1422	0.35%	ApiClientUtils.js	Network
71	1355	0.34%	QueryString.js	Utility
72	1345	0.34%	URIRFC3986.js	Polyfill	(-ish)
73	1342	0.33%	ES6Number.js	Polyfill
74	1281	0.32%	sdk.openMessenger.js	Utility
75	1275	0.32%	sdk.domReady.js	Utility
76	1226	0.31%	ES6Object.js	Polyfill
77	1182	0.30%	legacy:fb.event.js	Legacy
78	1159	0.29%	sdk.babelHelpers.js	Utility
79	1121	0.28%	ES5Object.js	Polyfill
80	1093	0.27%	URISchemes.js	Utility
81	1092	0.27%	sdk.URI.js	Utility
82	1065	0.27%	ES7Object.js	Polyfill
83	1055	0.26%	legacy:fb.compat.ui.js	Legacy
84	1043	0.26%	Miny.js	Utility
85	1010	0.25%	invariant.js	Utility
86	983	0.25%	sdk.Native.js	Utility	(only for inside native app?)
87	977	0.24%	sdk.Canvas.Tti.js	Canvas
88	916	0.23%	sdk.FeatureFunctor.js	Utility
89	906	0.23%	sdk.XFBML.CommentsCount.js	UI-related
90	888	0.22%	ex.js	Utility
91	886	0.22%	GlobalCallback.js	Utility
92	874	0.22%	sdk.Model.js	Utility
93	867	0.22%	UrlMap.js	Utility
94	859	0.21%	sdk.XFBML.ShareButton.js	UI-related
95	839	0.21%	ES6DatePrototype.js	Polyfill
96	806	0.20%	Log.js	Utility
97	790	0.20%	ES5FunctionPrototype.js	Polyfill
98	786	0.20%	eprintf.js	Utility
99	771	0.19%	sdk.Waitable.js	Utility
100	770	0.19%	containsNode.js	Utility