Is it possible to improve the execution performance of a query with 'simple' joins? The query is the following select statement:

select tbl1."DT_REF_TRANS", tbl1."VL_MTM",
       tbl1."VL_FUTURO", tbl1."DT_VENCIMENTO",
       tbl1."QT_PRAZODIASU", tbl1."ID_ATIVO_PASSIVO",
       tbl1."ID_CARTEIRA", tbl1."VL_MTM_ORIGEM",
       tbl1."ID_LOCAL_REGISTRO", tbl1."CD_NIVEL",
       tbl2."NO_ARQUIVO", tbl3."NO_PRODUTO",
       tbl3."ID_ENTRA_2804", tbl3."ID_ENTRA_VAR",
       tbl4."NO_MOEDA", tbl6."NO_SUBGRUPO",
       tbl5."NO_GRUPO_2804", tbl5."PERDA",
       tbl5."RENOVACAO", tbl5."PRZRENOV",
       tbl5."ANTECIPADU",
       tbl5."PRZANTECDU", tbl5."ANTECIPA",
       tbl5."DEPOSMAR", tbl5."RESERVA",
       tbl5."PERCATRASO",
       tbl5."PERCMORAM",
       tbl5."CALCATRASO", tbl5."NORMAL",
       tbl5."CODREGRA", tbl5."CODPRZAJU",
       tbl5."CD_NOVOMTM",
       tbl5."CD_DEPMARG",
       tbl5."ID_CONSOLIDA",
       tbl5."ID_TIPO_GRUPO",
       tbl7."NO_USUARIO_SIST",
       tbl8."NO_GRUPO_2804" as "GRUPOS_2804_NO_GRUPO_2804",
       tbl9."NO_GRUPO", "USUARIOS"."NO_USUARIO"
  from ((((((((("dbo".tbl1 tbl1
  left 
  join "dbo".tbl2 tbl2
       on (tbl2."CD_ARQUIVO" = tbl1."CD_ARQ_ORIGEM"))
  left
  join "dbo".tbl3 tbl3
       on (tbl3."CD_PRODUTO" = tbl1."CD_PRODUTO"))
  left
  join "dbo".tbl4 tbl4
       on (tbl4."CD_MOEDA" = tbl1."CD_MOEDA"))
  left 
  join "dbo".tbl6 tbl6
       on (tbl6."CD_SUBGRUPO" = tbl3."CD_SUBGRUPO"))
  left
  join "dbo".tbl5 tbl5
       on (tbl5."CD_GRUPO_2804" = tbl3."CD_GRUPO_2804"))
  left
  join "dbo".tbl7 tbl7
       on (tbl7."CD_USUARIO_SIST" = tbl5."CD_USUARIO_SIST"))
  left
  join "dbo".tbl8 tbl8
       on (tbl8."CD_GRUPO_2804" = tbl3."CD_GRUPO_2804"))
  inner join "dbo".tbl9 tbl9
       on (tbl9."CD_GRUPO" = tbl3."CD_GRUPO"))
  inner join "dbo"."USUARIOS" "USUARIOS"
       on ("USUARIOS"."CD_USUARIO" = tbl1."CD_NIVEL"))


You can see the execution plan here.

I've created and dropped indexes in columns inside the joins, have been testing with some hints ( like left loop join for example ( it helped me a lot in the past )). but, is there a way to improve a query that's not using where, or nothing else?

It's running in 30Seconds, returning 1M rows+.

Should I use IN somewhere? Exists? Some hint I don't know? 

See, the question is not "hot to update THIS query". I would like to know tips to improve queries using this structure in general.
Many outer joins are not a best option when dealing with big tables. In a nutshell, your plan might not be as optimal as it could be when using outer joins.

Wrong RENDA_FIXA table estimation is the reason why you are getting Parallelism and Hash joins everywhere even though you are not expecting many rows in the first place.

You can try OPTION (MAXDOP 1) hint to see if that any helps.
Also you should check statistics on RENDA_FIXA and GRUPOS_USER_2804 tables. 

The reason why you are getting that plan is because it expects 120,000 records, instead you're getting 1,800 that's why left loop joins helped you.

My advice is to try to deal with RENDA_FIXA table first, get the correct estimations out first, so the query optimizer could try to create a right plan.