Whilst playing classes like DK / Mage and Boomie i am having serious FPS problems whilst in combat. My main which is a warrior has no issues with this at all but atm playing my Unholy DK this has been a major issue.

Character data below;

build: v9.0.2-1.0.38
level: 60 (60)
class: DEATHKNIGHT
spec: unholy

talents: all_will_serve
army_of_the_damned
asphyxiate
soul_reaper
spell_eater
unholy_blight
unholy_pact

pvptalents: none

covenant: necrolord

conduits: brutal_grasp = 1
convocation_of_the_dead = 4
hardened_bones = 5
spirit_drain = 4

soulbinds: [plague_deviser_marileth]
oozs_frictionless_coating = 1
plagueborn_cleansing_slime = 1
volatile_solvent = 1

sets: none

gear: ardent_sunstar_signet = 1
baetheas_ironclad_warboots = 1
charm_of_eternal_winter = 1
darkmoon_deck_voracity = 1
decadent_nathrian_shawl = 1
fallen_templars_gauntlets = 1
gormshell_greaves = 1
muirnnes_stormforged_signet = 1
shadowghast_breastplate = 1
soldiers_stoneband_wristguards = 1
stoic_guardsmans_belt = 1
stone_legion_heraldry = 1
tabones_branded_pauldrons = 1
ulfius_calming_claymore = 1
wrathbark_greathelm = 1

legendaries: deadliest_coil = 1

itemIDs: 171412, 173087, 178694, 178701, 183013, 183025, 183031, 183035, 183040, 184027, 184778, 184783, 184796, 184804, 184809

settings: aoe = 2
buffPadding = 0
custom1Name = Custom 1
custom2Name = Custom 2
cycle = true
cycleDebuff = festering_wound
cycle_min = 6
damage = true
damageDots = false
damageExpiration = 8
damagePets = false
damageRange = 0
debuffPadding = 0
enabled = true
gcdSync = true
maxRefresh = 4
maxTime = 33
nameplateRange = 8
nameplates = true
package = Unholy
petbased = false
potion = potion_of_spectral_strength
potionsReset = 20180919.1
throttleRefresh = true
throttleTime = false
festermight_cycle = false

toggles: cooldowns = true
custom1 = false
custom2 = false
defensives = true
essences = true
interrupts = false
mode = automatic
potions = false

Any advice for this would be great.

Your options for managing performance are in /hek > spec > Performance.

Beyond that, I'm always looking for opportunities to improve efficiency but nothing I can offer you.

Longer, more complex priorities require more calculation time.

More displayed icons require more calculation time.

When submitting a ticket for any particular spec you're concerned with, please provide a snapshot taken at a time performance is an issue. It may help identify specific priorities that can be further tuned.