Well Reggie (it's easier than <unreg239u7m-98 2348yjftidopf>, I tried to confirm your situation, and no joy. I'm no expert, but my family and I are very happy with LW 4.0.5, and anticipating even more improvements.

Looks like something in your setup sux (or else it's the Pro difference). You should change the thread title to something more realistic: LW 4.05 is very good at downloading small files.

Here's what I tried:
-unzipped about 1 GB of files (mostly .jpg) to bring my shares up to 13K.
-upped the simultaneous downloads pref to 100
-searched for "wallpaper .jpg" (found about 350)
-tried to download most of them at once (~200?).
-1/2 hr later did a "Repeat Search"
- ~1/2 hr later selected ~100 "awaiting sources" and hit the Resume button
- waited another 1/2 hour, killed the dl's and resumed them from the Library->Incomplete folder (100 'blacks; 60 'reds')'

Here's what happened
-100 downloaded right off the bat (within a 1/2 hour) with no intervention.
-the gui 'froze' (mouse clicks didn't immediately change panes, etc, but no hangs or other problems: I was able to just leave it be, switch to another user account to check mail, browse, and twiddle my thumbs. Switched back, and all was good: Uploads were still proceeding, the connections pane was happily recording that Ultrapeer mode wasn't affected, and downloads showed quite a few dl's awaiting sources).
-After repeating search once; later resuming the "Awaitings;" and finally killing inactive downloads and resuming from the Library,
-Final count: 159 files

Notes
-CPU usage only a couple of times went over 50%, but usually stayed around 20-38%
-the most threads I saw recorded were 272
-real memory size peaked at 172 MB (VM 580 MB)

btw--I tried a "What's new", and saw a bunch of ethernet results. Huh? Turned out the kids were running LW Free downstairs the whole time.
A quick check showed they weren't sharing anything really offensive (Gad! they like "funny ads") Whew.

So:
-Looks like you have some good suggestions, but your system has other problems. LW 4.5 Pro handles small files quite well.
-I look forward to further optimizations, but right now your comments say more about your setup than LW IMHO. Maybe a slow old Mac with limited RAM and processor will help?


Specs:
18 month old 700 MHz PowerPC G3 iBook, 384 MB SDRAM; Linksys router (port 20300 opened and forwarded)->DOCSIS cable connection 5mbps down, 1mbps up). Sharing 13,152 files 5.15 GB (5,501,037,010 bytes)--mostly text and .jpg's, but also about 50 .mp3's and various other stuff.

LimeWire version 4.0.5 Pro
Java version 1.4.2_03 from Apple Computer, Inc.
Mac OS X v. 10.3.4 on ppc
Free/total memory: 8949904/73793536

-- listing session information --
Current thread: AWT-EventQueue-0
Active Threads: 218
Uptime: 1:44:54
Is Connected: true
Number of Ultrapeer -> Ultrapeer Connections: 30
Number of Ultrapeer -> Leaf Connections: 30
Number of Leaf -> Ultrapeer Connections: 0
Number of Old Connections: 0
Acting as Ultrapeer: true
Acting as Shielded Leaf: false
Number of Active Uploads: 3
Number of Queued Uploads: 0
Number of Active Managed Downloads: 2
Number of Active HTTP Downloaders: 1
Number of Waiting Downloads: 72
Received incoming this session: true
Number of Shared Files: 13152
Guess Capable: true

-- listing threads --
Acceptor: 1
AWT-Shutdown: 1
AWT-EventQueue-0: 1
pinger thread: 1
QRPPropagator: 1
MessageLoopingThread: 60
QueryDispatcher: 1
MulticastService: 1
HttpClient-ReferenceQueueThread: 1
TimerQueue: 1
UDPService-Receiver: 1
TimerRunner: 1
DownloadWorker: 1
OutputRunner: 60
ConnectionDispatchRunner: 4
QueryUnicaster: 1
ConnectionWatchdog: 1
DestroyJavaVM: 1
Java2D Disposer: 1
HttpClient-IdleConnectionThread: 1
Thread-3: 1
Thread-0: 1
HTTPAcceptor: 1
ManagedDownload: 74


-- listing properties --
WINDOW_Y=34
FORCE_IP_ADDRESS=true
WINDOW_X=68
PORT=20300
CLEAR_UPLOAD=false
FILTER_HTML=true
RUN_ON_STARTUP=false
SEARCH_MAGNETMIX_BUTTON=true
INSTALLED=true
FORCED_IP_ADDRESS_STRING=24.72.*.*
HARD_MAX_UPLOADS=10
AVERAGE_UPTIME=20385
TOTAL_UPTIME=978497
MAX_UPLOAD_BYTES_PER_SEC=295
COUNTRY=
LAST_SHUTDOWN_TIME=1085791178151
APP_WIDTH=809
SESSIONS=48
SHOW_TOTD=false
UPLOAD_SPEED=28
UPLOADS_PER_PERSON=1
FORCED_PORT=20300