Minimizing Lag During Basic Editing

Hello,

I'm a beginner at video editing so pardon my ignorance. I'm running Resolve 15 public beta (15.0.0B.046) on my Dell XPS 8920 (specs below) and am experiencing some lags, especially between transitions, during playback of 1080p video in the edit window. This happens even when no other filters like coloring or openFX are applied, simply one of the basic transitions. I am importing the media from an SSD external hard-drive. Is my system just a little under-qualified for basic editing or is there something I can do to speed up performance?
Many thanks in advance for any help!
System Specifications:

Dell XPS 8920
Core i7-1700 CPU @ 3.60 GHz 4 cores, 8 logical processors
24 GB installed RAM
AMD Radeon rx480 8GB
Dual In-Line Memory Module,16GB,2X8G,2400,U,N-E

I that is all that's important but here's the full specifications list in case more info is need. Sorry if this is way too much.

Module,Keyboard,104,United States,KB212B,W8,Ship In Box
Module,Dvd+/-Rw,8X,Hitachi Lg Data Storage,BARE,Across Line Of Business
Module,Cord,Power,120V,6 Ft
Module,Information,COMBLD,12M,Extreme Performance System,CRRS
MOD,SW,QFE,WIN10
MOD,CRD,GRPHC,RX,480,XPS,8920
MOD,CRD,NTWK,M2,3165AC,WW,CSMB
MOD-SRV,SW,XPS,8920
Module,Guide,Product,Safety/ Environmental And Regulatory Information,English,Dell Americas Organization
MOD,SW,DRE,CSMB
Module,Information,CFG 7-22,3700
Module,Software,DROPBOX,Factory Install
Module,Software,PULSE
Module,Information,NOSOUND,NOSPEAKER
Module,Software,Dolby Laboratories Licensing Corp,Optical Device Drive,License,Factory Install
Module,Chassis,460W,Active Power Factor Correction,Optical Device Drive,8920
Module,Software,COMMONBUILD,Across Line Of Business
Module,Label,UPC884116196433,7310
MOD,LBL,REG,XPS,JSD2,8920,460W
Module,Software, CYB,MPEG2,W8
Module,Software,Soft Contracts,Consumer,ALL
Module,Software,DELL-UPDATE
Module,Software,KS,Registration
Module,Solid State Drive,256,P34,80S3,Technical Sheet,XG4
Module,Screw,M.2,Software Support Diskette,R5/VM
Module,Mouse,6BTN,Laser Consumer,Logitech,Desktop
MOD,SW,WIN10,64,ENGLISH,WW
Module,Software,PKTCLD,Factory Install
Module,Label,Regulatory,T7610,Dell Americas Organization
Module,Dual In-Line Memory Module,16GB,2X8G,2400,U,N-E
Module,Software,OFCTOPK,Multiple User Interface,Factory Install
Module,Information,C2,MSSR0,R730
Module,Shipping Material,System,XPS8920,76675
MOD,SW,APP,SACLIENT
Service Install Module,Software,DW1703/4,5320
Module,Hard Drive,1TB,7.2K,#2,512E,OASIS
MOD,SW,W10,EDITION,HOME
Module,Software,Cyberlink,Suite,ESLS,2.0,Digital Video Disk Drive
MOD,SW,DPK,W10H,HE
Module,Thermal,Heatsink,65W,8900
MOD,LBL,INTEL,CI7,7,SML
Ship Group,Extreme Performance System,L10,8910,Foxconn,Dell Americas Organization
MOD,PRC,KBL,I7-7700,3.6G,65W
MOD-SRV,SW,WLAN/BT,3165,8920
Module,Dual In-Line Memory Module,8GB,2X4G,2400,U,Non-Error Correcting Code
Module,Information,Multipack,Medium Tower,4-PK,D3
Information,Equipment
Onsite/In-Home Service After Remote Diagnosis, 1 Year
Module,Technical Sheet Warranty,Dell Americas Organization
Dell Limited Hardware Warranty Initial Year

Thanks!