Gas used by tx increases sharply for accounts owning a large number of tokens

[shilei-wang]

Describe the bug
Not sure if it is a bug ， but maybe we need to pay attention to it.

It is observed that ALL TXs signed by this user will consume large amounts of Gas .

To Reproduce

for example:
if the user owns only IRIS, one delegate TX consumes him 16000 gas.

if the user owns mays 30 kinds of assets, one delegate TX consumes him 107213 gas.

---

echo 1234567890 | iriscli stake delegate --address-validator=fva1gzkaggvw6gguendvq4tz0wn6hkkauynardljrm --amount=5iris --fee=0.004iris --commit  --from=v1  --chain-id=shilei-qa --gas=150000 --fee=31iris

Committed at block 400 (tx hash: B62E04C42B370120D308A6E8DB8C8CCEE0584B0E7DAF49C5D5AFA4F606726D1A, response:
 {
   "code": 0,
   "data": null,
   "log": "Msg 0: ",
   "info": "",
   "gas_wanted": 150000,
   "gas_used": 107213,
   "codespace": "",
   "tags": [
     {
       "key": "action",
       "value": "delegate"
     },
     {
       "key": "delegator",
       "value": "faa1gzkaggvw6gguendvq4tz0wn6hkkauynaku4a7u"
     },
     {
       "key": "destination-validator",
       "value": "fva1gzkaggvw6gguendvq4tz0wn6hkkauynardljrm"
     }
   ]
 })

[shilei-wang]

tokens send issue-token
1 : 3859 5238
20: 4004 5498
100: 4084 5679

[shilei-wang]

gasLog = 1.08
send issue-token delegate
1 : 3890 5682 5538
20: 4071 6004 6908
100: 4169 6224 7077

gasLog = 1.05
send issue-token delegate
1 : 4222 6991 6921
20: 4520 7511 8934
100: 4675 7857 9187

gasLog = 1.03
send issue-token delegate
1 : 4809 9328 9407
20: 5312 10180 12497
100: 5567 10757 12928

[shilei-wang]

gasLog = 1.01
send issue-token delegate
1 : 7758 9328 21729