Code (Text):

1. command /test:
2.     trigger:
3.         set {_center} to location of player
4.         set {_radius} to 180 #radius of sphere in blocks
5.         set {_density} to 250 # density (higher value -> more particles -> more performance impact)
6.  
7.         set {_density} to {_radius}/{_density}
8.         set {_i} to 0
9.         while ({_i} <= 180):
10.             set {_shift} to sin({_i}) * {_radius}
11.             set {_y} to cos({_i}) * {_radius}
12.             set {_a} to 0
13.             while ({_a} < 180):
14.                 set {_x} to cos({_a}) * {_shift}
15.                 set {_z} to sin({_a}) * {_shift}
16.                 show wax on at ({_center} ~ vector({_x},{_y},{_z}))
17.                 show wax on at ({_center} ~ vector(0-{_x},{_y},0-{_z}))
18.                 add {_density} to {_a}
19.             add {_density} to {_i}

For optimize you can save locations before sending particles, if center is known before
replace lines 16, 17 with

Code (Text):

1.      add 1 to {_index}
2.      set {spheres::mysphere::%{_index}%} to ({_center} ~ vector({_x},{_y},{_z}))
3.      add 1 to {_index}
4.      set {spheres::mysphere::%{_index}%} to ({_center} ~ vector(0-{_x},{_y},0-{_z}))

then simply run code when need show precalculated sphere

Code (Text):

1. loop {spheres::mysphere::*}:
2.     show wax on at loop-value

 

idk, I test my code on 1.19.2, with Skript 2.6.3, its crashes only if put high density with low radius or high density with high radius, with values what I set in code - no lags.

 

But timed out without crash isn't code problem, your's client cant perform all particle packets

 

Var 1: World border can be send per player as packet. This is implemented in Skbee addon for example.
Var 2: Using complex addon for work with particle system, as SkDragon, updated fork link
Var 3: Learn some basics and explore code what I send before, because it's works, idk what problem with your's server/client software