Actually, even when connected & plugged, memory use eventually creeps up
to the amounts noted in first post.  My emacs instance currently has
386MB virtual and 281MB residence sizes.  The output from memory-usage
(with some details elided for confidentiality) is interesting:

Garbage collection stats:
((conses 8 3121117 309714) (symbols 24 80506 326) (miscs 20 26942 22925) (strings 16 377132 42952) (string-bytes 1 8858270) (vectors 8 145631) (vector-slots 4 4148946 77750) (floats 8 15329 1137) (intervals 28 287150 2991) (buffers 520 196))

 =>	23.8MB (+ 2.36MB dead) in conses
	1.84MB (+ 7.64kB dead) in symbols
	 526kB (+  448kB dead) in miscs
	5.75MB (+  671kB dead) in strings
	8.45MB in string-bytes
	1.11MB in vectors
	15.8MB (+  304kB dead) in vector-slots
	 120kB (+ 8.88kB dead) in floats
	7.67MB (+ 81.8kB dead) in intervals
	99.5kB in buffers

Total in lisp objects: 69.0MB (live 65.2MB, dead 3.85MB)

Buffer ralloc memory usage:
90 buffers
 129MB total (98.1MB in gaps)
      Size	Gap	Name

  27786240	7510767	 *Gnus agent overview*
    672589	2000	notes.org
    653499	2000	research.org
    564524	2000	teaching.org
    480744	2000	jmp.org
    379216	2000	bbdb
    285221	2000	admin.org
    266407	1177	tasks.org
    213159	2000	personal.org
    185383	1909	newsrc-dribble
    167436	2000	diary.org
    113940	1654	*imap log*
    109635	2000	org-clock.el
    107743	2000	studyabroad.org
     94245	2000	mobileorginbox.org
     82731	2000	log.org
     62550	2000	outlook.org
     50084	2000	 *nnimap outlook.office365.com nil  *nntpd**-655785
     50076	1946	 *nnimap outlook.office365.com nil  *nntpd**-514307
     50073	1949	 *nnimap outlook.office365.com nil  *nntpd**
     49579	1946	 *nnimap outlook.office365.com nil  *nntpd**-752666
     45658	2117	talk.org
     33127	1084	*Messages*
     26946	392446	 *nnimap imap.gmail.com 993  *nntpd**-631837
     25578	15581	 *nnimap imap.gmail.com 993  *nntpd**-100704
     24546	714	 *nnimap imap.gmail.com 993  *nntpd**-432908
     23512	2000	 *Gnus Backlog*
     20747	65132	*Org PDF LaTeX Output*
     13977	9405	 *gnus article copy*
      9155	1490	 *nnimap imap.mail.yahoo.com 993  *nntpd**-372452
      9045	1493	 *nnimap imap.mail.yahoo.com 993  *nntpd**
      8974	1971	 *nnimap imap.mail.yahoo.com 993  *nntpd**-722285
      4578	5595	 *server news.gwene.org nntp  *nntpd**
      4568	1775	 *nnimap imap.gmail.com 993  *nntpd**-895308
      3271	773	*Group*
      2535	1969	memstats.org
      2535	2000	 *code-converting-work*
      2057	0	 *org-src-fontification:ledger-mode*
      1474	691	*Org Agenda(a)*
      1398	2000	dropbox.org
      1314	731	*gnuplot*
       911	1999	*Org Clock*
       764	1852	 *Agenda Commands*
       745	1283	*eshell*
       731	1534	*Buffer Details*
       491	1577	 *nnimap imap.gmail.com 993  *nntpd**
       488	1578	 *nnimap imap.gmail.com 993  *nntpd**-97134
       488	1579	 *nnimap imap.gmail.com 993  *nntpd**-72848
       488	1580	 *nnimap imap.gmail.com 993  *nntpd**-347817
       210	1811	*Fancy Diary Entries*
       191	2936	 *org-src-fontification:latex-mode*
       145	2009	*vc*
       141	2000	*scratch*
        76	1999	*Compile-Log*
        71	1999	*WoMan-Log*
        56	2000	diary
        44	6296	 *icalendar-work*
        38	2138	 *gnus work*
        35	2000	 *Minibuf-0*
        34	2000	 *Org-Babel Error*
        34	2000	*Org-Babel Error Output*
        33	94356933	 *nntpd*
        29	2000	ledgerrc
        14	2019	 *canonical address*
        13	255084	 *code-conversion-work*
         3	2025	 *Echo Area 0*
         3	2021	 *Echo Area 1*
         0	2549	 *Minibuf-1*
         0	2021	*BBDB*
         0	20	 *EMMS Playlist*
         0	20	*ESS*
         0	2033	 *extract address components*
         0	20	 *Async Prefetch Article*
         0	20	 *MML2015 Result*
         0	20	*Async Shell Command*
         0	20	*Quail Completions*

-- 
: Eric S Fraga
: in Emacs 25.2.2 + Gnus v5.13 + evil-git-bdeb602
: BBDB version 3.1.2 (2017-01-30 14:47:26+00:00)